R/main.R
In kkrismer/transite: RNA-binding protein motif analysis
Defines functions
run_kmer_spma
run_kmer_tsma
run_matrix_spma
run_matrix_tsma
Documented in
run_kmer_spma
run_kmer_tsma
run_matrix_spma
run_matrix_tsma
#' @title Matrix-based Transcript Set Motif Analysis
#'
#' @description
#' Calculates motif enrichment in foreground sets versus a background
#' set using position
#' weight matrices to identify putative binding sites
#'
#' @param foreground_sets a list of named character vectors of
#' foreground sequences
#' (only containing upper case characters A, C, G, T), where the
#' names are RefSeq identifiers
#' and sequence
#' type qualifiers (\code{"3UTR"}, \code{"5UTR"}, \code{"mRNA"}), e.g.
#' \code{"NM_010356|3UTR"}. Names are only used to cache results.
#' @param background_set a named character vector of background
#' sequences (naming follows same
#' rules as foreground set sequences)
#' @inheritParams score_transcripts
#' @inheritParams calculate_motif_enrichment
#'
#' @return A list with the following components:
#' \tabular{rl}{
#' \code{foreground_scores} \tab the result of \code{\link{score_transcripts}}
#' for the foreground
#' sets\cr
#' \code{background_scores} \tab the result of \code{\link{score_transcripts}}
#' for the background
#' set\cr
#' \code{enrichment_dfs} \tab a list of data frames, returned by
#' \code{\link{calculate_motif_enrichment}}
#' }
#'
#' @details
#' Motif transcript set analysis can be used to identify RNA binding proteins,
#' whose targets are
#' significantly overrepresented or underrepresented in certain sets of
#' transcripts.
#'
#' The aim of Transcript Set Motif Analysis (TSMA) is to identify the
#' overrepresentation
#' and underrepresentation of potential RBP targets (binding sites)
#' in a set (or sets) of
#' sequences, i.e., the foreground set, relative to the entire population
#' of sequences.
#' The latter is called background set, which can be composed of all
#' sequences of the genes
#' of a microarray platform or all sequences of an organism or any
#' other meaningful
#' superset of the foreground sets.
#'
#' The matrix-based approach skips the \emph{k}-merization step of
#' the \emph{k}-mer-based approach
#' and instead scores the transcript sequence as a whole with a
#' position specific scoring matrix.
#'
#' For each sequence in foreground and background sets and each
#' sequence motif,
#' the scoring algorithm evaluates the score for each sequence position.
#' Positions with
#' a relative score greater than a certain threshold are considered hits, i.e.,
#' putative binding sites.
#'
#' By scoring all sequences in foreground and background sets, a hit count
#' for each motif and
#' each set is obtained, which is used to calculate enrichment values and
#' associated p-values
#' in the same way in which motif-compatible hexamer enrichment values are
#' calculated in
#' the k -mer-based approach. P-values are adjusted with one of the available
#' adjustment methods.
#'
#' An advantage of the matrix-based approach is the possibility of detecting
#' clusters of
#' binding sites. This can be done by counting regions with many hits using
#' positional
#' hit information or by simply applying a hit count threshold per sequence,
#' e.g., only
#' sequences with more than some number of hits are considered. Homotypic
#' clusters of RBP
#' binding sites may play a similar role as clusters of transcription factors.
#'
#' @examples
#' # define simple sequence sets for foreground and background
#' foreground_set1 <- c(
#' "CAACAGCCUUAAUU", "CAGUCAAGACUCC", "CUUUGGGGAAU",
#' "UCAUUUUAUUAAA", "AAUUGGUGUCUGGAUACUUCCCUGUACAU",
#' "AUCAAAUUA", "AGAU", "GACACUUAAAGAUCCU",
#' "UAGCAUUAACUUAAUG", "AUGGA", "GAAGAGUGCUCA",
#' "AUAGAC", "AGUUC", "CCAGUAA"
#' )
#' names(foreground_set1) <- c(
#' "NM_1_DUMMY|3UTR", "NM_2_DUMMY|3UTR", "NM_3_DUMMY|3UTR",
#' "NM_4_DUMMY|3UTR", "NM_5_DUMMY|3UTR", "NM_6_DUMMY|3UTR",
#' "NM_7_DUMMY|3UTR",
#' "NM_8_DUMMY|3UTR", "NM_9_DUMMY|3UTR", "NM_10_DUMMY|3UTR",
#' "NM_11_DUMMY|3UTR",
#' "NM_12_DUMMY|3UTR", "NM_13_DUMMY|3UTR", "NM_14_DUMMY|3UTR"
#' )
#'
#' foreground_set2 <- c("UUAUUUA", "AUCCUUUACA", "UUUUUUU", "UUUCAUCAUU")
#' names(foreground_set2) <- c(
#' "NM_15_DUMMY|3UTR", "NM_16_DUMMY|3UTR", "NM_17_DUMMY|3UTR",
#' "NM_18_DUMMY|3UTR"
#' )
#'
#' foreground_sets <- list(foreground_set1, foreground_set2)
#'
#' background_set <- c(
#' "CAACAGCCUUAAUU", "CAGUCAAGACUCC", "CUUUGGGGAAU",
#' "UCAUUUUAUUAAA", "AAUUGGUGUCUGGAUACUUCCCUGUACAU",
#' "AUCAAAUUA", "AGAU", "GACACUUAAAGAUCCU",
#' "UAGCAUUAACUUAAUG", "AUGGA", "GAAGAGUGCUCA",
#' "AUAGAC", "AGUUC", "CCAGUAA",
#' "UUAUUUA", "AUCCUUUACA", "UUUUUUU", "UUUCAUCAUU",
#' "CCACACAC", "CUCAUUGGAG", "ACUUUGGGACA", "CAGGUCAGCA"
#' )
#' names(background_set) <- c(
#' "NM_1_DUMMY|3UTR", "NM_2_DUMMY|3UTR", "NM_3_DUMMY|3UTR",
#' "NM_4_DUMMY|3UTR", "NM_5_DUMMY|3UTR", "NM_6_DUMMY|3UTR",
#' "NM_7_DUMMY|3UTR",
#' "NM_8_DUMMY|3UTR", "NM_9_DUMMY|3UTR", "NM_10_DUMMY|3UTR",
#' "NM_11_DUMMY|3UTR",
#' "NM_12_DUMMY|3UTR", "NM_13_DUMMY|3UTR", "NM_14_DUMMY|3UTR",
#' "NM_15_DUMMY|3UTR",
#' "NM_16_DUMMY|3UTR", "NM_17_DUMMY|3UTR", "NM_18_DUMMY|3UTR",
#' "NM_19_DUMMY|3UTR",
#' "NM_20_DUMMY|3UTR", "NM_21_DUMMY|3UTR", "NM_22_DUMMY|3UTR"
#' )
#'
#' # run cached version of TSMA with all Transite motifs (recommended):
#' # results <- run_matrix_tsma(foreground_sets, background_set)
#'
#' # run uncached version with one motif:
#' motif_db <- get_motif_by_id("M178_0.6")
#' results <- run_matrix_tsma(foreground_sets, background_set, motifs = motif_db,
#' cache = FALSE)
#'
#' \dontrun{
#' # define example sequence sets for foreground and background
#' foreground1_df <- transite:::ge$foreground1_df
#' foreground_set1 <- gsub("T", "U", foreground1_df$seq)
#' names(foreground_set1) <- paste0(foreground1_df$refseq, "|",
#' foreground1_df$seq_type)
#'
#' foreground2_df <- transite:::ge$foreground2_df
#' foreground_set2 <- gsub("T", "U", foreground2_df$seq)
#' names(foreground_set2) <- paste0(foreground2_df$refseq, "|",
#' foreground2_df$seq_type)
#'
#' foreground_sets <- list(foreground_set1, foreground_set2)
#'
#' background_df <- transite:::ge$background_df
#' background_set <- gsub("T", "U", background_df$seq)
#' names(background_set) <- paste0(background_df$refseq, "|",
#' background_df$seq_type)
#'
#' # run cached version of TSMA with all Transite motifs (recommended)
#' results <- run_matrix_tsma(foreground_sets, background_set)
#'
#' # run uncached version of TSMA with all Transite motifs
#' results <- run_matrix_tsma(foreground_sets, background_set, cache = FALSE)
#'
#' # run TSMA with a subset of Transite motifs
#' results <- run_matrix_tsma(foreground_sets, background_set,
#' motifs = get_motif_by_rbp("ELAVL1"))
#'
#' # run TSMA with user-defined motif
#' toy_motif <- create_matrix_motif(
#' "toy_motif", "example RBP", toy_motif_matrix,
#' "example type", "example species", "user"
#' )
#' results <- run_matrix_tsma(foreground_sets, background_set,
#' motifs = list(toy_motif))
#' }
#'
#' @family TSMA functions
#' @family matrix functions
#' @importFrom dplyr arrange
#' @export
run_matrix_tsma <- function(foreground_sets,
background_set,
motifs = NULL,
max_hits = 5,
threshold_method = "p_value",
threshold_value = 0.25^6,
max_fg_permutations = 1000000,
min_fg_permutations = 1000,
e = 5,
p_adjust_method = "BH",
n_cores = 1,
cache = paste0(tempdir(), "/sc/")) {
# avoid CRAN note
adj_p_value <- p_value <- NULL
i <- 1
foreground_scores <-
lapply(foreground_sets, function(foreground_set) {
result <-
score_transcripts(
foreground_set,
motifs = motifs,
max_hits = max_hits,
threshold_method = threshold_method,
threshold_value = threshold_value,
n_cores = n_cores,
cache = cache
)
message(paste0("scored transcripts in foreground set ", i))
i <<- i + 1
return(result)
})
background_scores <-
score_transcripts(
background_set,
motifs = motifs,
max_hits = max_hits,
threshold_method = threshold_method,
threshold_value = threshold_value,
n_cores = n_cores,
cache = cache
)
message("scored transcripts in background set")
i <- 1
enrichment_dfs <-
lapply(foreground_scores, function(scores_per_condition) {
enrichment_df <-
calculate_motif_enrichment(
scores_per_condition$df,
background_scores$df,
background_scores$total_sites,
background_scores$absolute_hits,
length(foreground_sets[[i]]),
max_fg_permutations = max_fg_permutations,
min_fg_permutations = min_fg_permutations,
e = e,
p_adjust_method = p_adjust_method
)
enrichment_df <-
dplyr::arrange(enrichment_df, adj_p_value, p_value)
message(paste0("calculated enrichment for foreground set ", i))
i <<- i + 1
return(enrichment_df)
})
return(
list(
foreground_scores = foreground_scores,
background_scores = background_scores,
enrichment_dfs = enrichment_dfs
)
)
}
#' @title Matrix-based Spectrum Motif Analysis
#'
#' @description
#' SPMA helps to illuminate the relationship between RBP binding
#' evidence and the transcript
#' sorting criterion, e.g., fold change between treatment and control samples.
#'
#' @param sorted_transcript_sequences named character vector of ranked sequences
#' (only containing upper case characters A, C, G, T), where the
#' names are RefSeq identifiers and sequence
#' type qualifiers (\code{"3UTR"}, \code{"5UTR"} or \code{"mRNA"}), separated by
#' \code{"|"}, e.g.
#' \code{"NM_010356|3UTR"}. Names are only used to cache results.
#' The sequences in \code{sorted_transcript_sequences} must be ranked
#' (i.e., sorted).
#' Commonly used sorting criteria are measures of differential expression, such
#' as fold change or signal-to-noise ratio (e.g., between treatment and control
#' samples in gene expression profiling experiments).
#' @inheritParams run_matrix_tsma
#' @inheritParams subdivide_data
#' @inheritParams score_spectrum
#'
#' @return A list with the following components:
#' \tabular{rl}{
#' \code{foreground_scores} \tab the result of \code{\link{score_transcripts}}
#' for the foreground
#' sets (the bins)\cr
#' \code{background_scores} \tab the result of \code{\link{score_transcripts}}
#' for the background
#' set\cr
#' \code{enrichment_dfs} \tab a list of data frames, returned by
#' \code{\link{calculate_motif_enrichment}}\cr
#' \code{spectrum_info_df} \tab a data frame with the SPMA results\cr
#' \code{spectrum_plots} \tab a list of spectrum plots, as generated by
#' \code{\link{score_spectrum}}\cr
#' \code{classifier_scores} \tab a list of classifier scores, as returned by
#' \code{\link{classify_spectrum}}
#' }
#'
#' @details
#' In order to investigate how motif targets are distributed across a
#' spectrum of
#' transcripts (e.g., all transcripts of a platform, ordered by fold change),
#' Spectrum Motif Analysis visualizes the gradient of RBP binding evidence
#' across all transcripts.
#'
#' The matrix-based approach skips the \emph{k}-merization step of the
#' \emph{k}-mer-based approach
#' and instead scores the transcript sequence as a whole with a position
#' specific scoring matrix.
#'
#' For each sequence in foreground and background sets and each sequence motif,
#' the scoring algorithm evaluates the score for each sequence position.
#' Positions with
#' a relative score greater than a certain threshold are considered hits, i.e.,
#' putative binding sites.
#'
#' By scoring all sequences in foreground and background sets, a hit count
#' for each motif and
#' each set is obtained, which is used to calculate enrichment values and
#' associated p-values
#' in the same way in which motif-compatible hexamer enrichment values are
#' calculated in
#' the \emph{k}-mer-based approach. P-values are adjusted with one of the
#' available adjustment methods.
#'
#' An advantage of the matrix-based approach is the possibility of detecting
#' clusters of
#' binding sites. This can be done by counting regions with many hits using
#' positional
#' hit information or by simply applying a hit count threshold per
#' sequence, e.g., only
#' sequences with more than some number of hits are considered. Homotypic
#' clusters of RBP
#' binding sites may play a similar role as clusters of transcription factors.
#'
#' @examples
#' # example data set
#' background_df <- transite:::ge$background_df
#' # sort sequences by signal-to-noise ratio
#' background_df <- dplyr::arrange(background_df, value)
#' # character vector of named and ranked (by signal-to-noise ratio) sequences
#' background_seqs <- gsub("T", "U", background_df$seq)
#' names(background_seqs) <- paste0(background_df$refseq, "|",
#' background_df$seq_type)
#'
#' results <- run_matrix_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "signal-to-noise ratio",
#' motifs = get_motif_by_id("M178_0.6"),
#' n_bins = 20,
#' max_fg_permutations = 10000)
#'
#' \dontrun{
#' results <- run_matrix_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "SNR") }
#'
#' @family SPMA functions
#' @family matrix functions
#' @importFrom stats p.adjust
#' @importFrom dplyr filter
#' @export
run_matrix_spma <- function(sorted_transcript_sequences,
sorted_transcript_values = NULL,
transcript_values_label = "transcript value",
motifs = NULL,
n_bins = 40,
midpoint = 0,
x_value_limits = NULL,
max_model_degree = 1,
max_cs_permutations = 10000000,
min_cs_permutations = 5000,
max_hits = 5,
threshold_method = "p_value",
threshold_value = 0.25^6,
max_fg_permutations = 1000000,
min_fg_permutations = 1000,
e = 5,
p_adjust_method = "BH",
n_cores = 1,
cache = paste0(tempdir(), "/sc/")) {
# avoid CRAN note
motif_id <- motif_rbps <- adj_r_squared <- degree <-
residuals <- slope <- NULL
f_statistic <- f_statistic_p_value <- f_statistic_adj_p_value <- NULL
consistency_score <-
consistency_score_p_value <-
consistency_score_adj_p_value <-
consistency_score_n <- NULL
n_significant <-
n_very_significant <-
n_extremely_significant <-
aggregate_classifier_score <- NULL
foreground_sets <- subdivide_data(sorted_transcript_sequences, n_bins)
results <- run_matrix_tsma(
foreground_sets,
sorted_transcript_sequences,
motifs = motifs,
max_hits = max_hits,
threshold_method = threshold_method,
threshold_value = threshold_value,
max_fg_permutations = max_fg_permutations,
min_fg_permutations = min_fg_permutations,
e = e,
p_adjust_method = p_adjust_method,
n_cores = n_cores,
cache = cache
)
if (length(results$enrichment_dfs) > 0) {
enrichment_df <- do.call("rbind", results$enrichment_dfs)
enrichment_df$adj_p_value <-
stats::p.adjust(enrichment_df$p_value, method = p_adjust_method)
if (is.null(motifs)) {
motifs <- get_motifs()
}
spectrum_info <- lapply(motifs, function(motif) {
motif_data_df <- dplyr::filter(enrichment_df,
motif_id == get_id(motif))
values <- motif_data_df$enrichment
values[values == 0] <-
0.01 # avoid -Inf after taking the log
score <-
score_spectrum(
log(values),
p_values = motif_data_df$adj_p_value,
sorted_transcript_values = sorted_transcript_values,
transcript_values_label = transcript_values_label,
midpoint = midpoint,
x_value_limits = x_value_limits,
max_model_degree = max_model_degree,
max_cs_permutations = max_cs_permutations,
min_cs_permutations = min_cs_permutations
)
n_significant <-
sum(motif_data_df$adj_p_value <= 0.05)
classifier_score <-
classify_spectrum(
get_adj_r_squared(score),
get_model_degree(score),
get_model_slope(score),
get_consistency_score_n(score),
n_significant,
n_bins
)
return(
list(
info = list(
motif_id = get_id(motif),
motif_rbps = paste(get_rbps(motif), collapse = ", "),
adj_r_squared = get_adj_r_squared(score),
degree = get_model_degree(score),
residuals = get_model_residuals(score),
slope = get_model_slope(score),
f_statistic = get_model_f_statistic(score),
f_statistic_p_value = get_model_f_statistic_p_value(score),
consistency_score = get_consistency_score(score),
consistency_score_p_value = get_consistency_score_p_value(score),
consistency_score_n = get_consistency_score_n(score),
n_significant = n_significant,
n_very_significant = sum(motif_data_df$adj_p_value <= 0.01),
n_extremely_significant = sum(motif_data_df$adj_p_value <= 0.001),
aggregate_classifier_score = sum(classifier_score)
),
spectrum_plot = score@plot,
classifier_score = classifier_score
)
)
})
spectrum_info_df <-
as.data.frame(do.call("rbind", lapply(spectrum_info, function(x)
x$info)),
stringsAsFactors = FALSE
)
spectrum_info_df$motif_id <-
as.character(spectrum_info_df$motif_id)
spectrum_info_df$motif_rbps <-
as.character(spectrum_info_df$motif_rbps)
spectrum_info_df$adj_r_squared <-
as.numeric(spectrum_info_df$adj_r_squared)
spectrum_info_df$degree <-
as.integer(spectrum_info_df$degree)
spectrum_info_df$residuals <-
as.numeric(spectrum_info_df$residuals)
spectrum_info_df$slope <-
as.numeric(spectrum_info_df$slope)
spectrum_info_df$f_statistic <-
as.numeric(spectrum_info_df$f_statistic)
spectrum_info_df$f_statistic_p_value <-
as.numeric(spectrum_info_df$f_statistic_p_value)
spectrum_info_df$consistency_score <-
as.numeric(spectrum_info_df$consistency_score)
spectrum_info_df$consistency_score_p_value <-
as.numeric(spectrum_info_df$consistency_score_p_value)
spectrum_info_df$consistency_score_n <-
as.integer(spectrum_info_df$consistency_score_n)
spectrum_info_df$n_significant <-
as.integer(spectrum_info_df$n_significant)
spectrum_info_df$n_very_significant <-
as.integer(spectrum_info_df$n_very_significant)
spectrum_info_df$n_extremely_significant <-
as.integer(spectrum_info_df$n_extremely_significant)
spectrum_info_df$aggregate_classifier_score <-
as.integer(spectrum_info_df$aggregate_classifier_score)
spectrum_info_df$f_statistic_adj_p_value <-
stats::p.adjust(spectrum_info_df$f_statistic_p_value,
method = p_adjust_method)
spectrum_info_df$consistency_score_adj_p_value <-
stats::p.adjust(spectrum_info_df$consistency_score_p_value,
method = p_adjust_method)
spectrum_info_df <-
dplyr::select(
spectrum_info_df,
motif_id,
motif_rbps,
adj_r_squared,
degree,
residuals,
slope,
f_statistic,
f_statistic_p_value,
f_statistic_adj_p_value,
consistency_score,
consistency_score_p_value,
consistency_score_adj_p_value,
consistency_score_n,
n_significant,
n_very_significant,
n_extremely_significant,
aggregate_classifier_score
)
spectrum_plots <-
lapply(spectrum_info, function(x)
x$spectrum_plot)
classifier_scores <-
lapply(spectrum_info, function(x)
x$classifier_score)
} else {
stop("empty foreground sets")
}
return(
list(
foreground_scores = results$foreground_scores,
background_scores = results$background_scores,
enrichment_dfs = results$enrichment_dfs,
spectrum_info_df = spectrum_info_df,
spectrum_plots = spectrum_plots,
classifier_scores = classifier_scores
)
)
}
#' @title \emph{k}-mer-based Transcript Set Motif Analysis
#'
#' @description
#' Calculates the enrichment of putative binding sites in foreground sets
#' versus a background set
#' using \emph{k}-mers to identify putative binding sites
#'
#' @param motifs a list of motifs that is used to score the specified sequences.
#' If \code{is.null(motifs)} then all Transite motifs are used.
#' @param fg_permutations numer of foreground permutations
#' @param kmer_significance_threshold p-value threshold for significance,
#' e.g., \code{0.05} or
#' \code{0.01} (used for volcano plots)
#' @param produce_plot if \code{TRUE} volcano plots and distribution plots
#' are created
#' @param p_combining_method one of the following: Fisher (1932)
#' (\code{"fisher"}), Stouffer (1949),
#' Liptak (1958) (\code{"SL"}), Mudholkar and George (1979)
#' (\code{"MG"}), and Tippett (1931)
#' (\code{"tippett"}) (see \code{\link{p_combine}})
#' @inheritParams calculate_kmer_enrichment
#'
#' @return A list of lists (one for each transcript set) with the
#' following components:
#' \tabular{rl}{
#' \code{enrichment_df} \tab the result of
#' \code{\link{compute_kmer_enrichment}} \cr
#' \code{motif_df} \tab \cr
#' \code{motif_kmers_dfs} \tab \cr
#' \code{volcano_plots} \tab volcano plots for each
#' motif (see \code{\link{draw_volcano_plot}}) \cr
#' \code{perm_test_plots} \tab plots of the empirical distribution of
#' \emph{k}-mer enrichment values for each motif \cr
#' \code{enriched_kmers_combined_p_values} \tab \cr
#' \code{depleted_kmers_combined_p_values} \tab
#' }
#'
#' @details
#' Motif transcript set analysis can be used to identify RNA binding
#' proteins, whose targets are
#' significantly overrepresented or underrepresented in certain sets
#' of transcripts.
#'
#' The aim of Transcript Set Motif Analysis (TSMA) is to identify the
#' overrepresentation
#' and underrepresentation of potential RBP targets (binding sites)
#' in a set (or sets) of
#' sequences, i.e., the foreground set, relative to the entire population
#' of sequences.
#' The latter is called background set, which can be composed of all
#' sequences of the genes
#' of a microarray platform or all sequences of an organism or any
#' other meaningful
#' superset of the foreground sets.
#'
#' The \emph{k}-mer-based approach breaks the sequences of foreground
#' and background sets into
#' \emph{k}-mers and calculates the enrichment on a \emph{k}-mer level.
#' In this case, motifs are
#' not represented as position weight matrices, but as lists of \emph{k}-mers.
#'
#' Statistically significantly enriched or depleted \emph{k}-mers
#' are then used to
#' calculate a score for each RNA-binding protein, which quantifies its
#' target overrepresentation.
#'
#' @examples
#' # define simple sequence sets for foreground and background
#' foreground_set1 <- c(
#' "CAACAGCCUUAAUU", "CAGUCAAGACUCC", "CUUUGGGGAAU",
#' "UCAUUUUAUUAAA", "AAUUGGUGUCUGGAUACUUCCCUGUACAU",
#' "AUCAAAUUA", "AGAU", "GACACUUAAAGAUCCU",
#' "UAGCAUUAACUUAAUG", "AUGGA", "GAAGAGUGCUCA",
#' "AUAGAC", "AGUUC", "CCAGUAA"
#' )
#' foreground_set2 <- c("UUAUUUA", "AUCCUUUACA", "UUUUUUU", "UUUCAUCAUU")
#' foreground_sets <- list(foreground_set1, foreground_set2)
#' background_set <- unique(c(foreground_set1, foreground_set2, c(
#' "CCACACAC", "CUCAUUGGAG", "ACUUUGGGACA", "CAGGUCAGCA",
#' "CCACACCGG", "GUCAUCAGU", "GUCAGUCC", "CAGGUCAGGGGCA"
#' )))
#'
#' # run k-mer based TSMA with all Transite motifs (recommended):
#' # results <- run_kmer_tsma(foreground_sets, background_set)
#'
#' # run TSMA with one motif:
#' motif_db <- get_motif_by_id("M178_0.6")
#' results <- run_kmer_tsma(foreground_sets, background_set, motifs = motif_db)
#' \dontrun{
#' # define example sequence sets for foreground and background
#' foreground_set1 <- gsub("T", "U", transite:::ge$foreground1_df$seq)
#' foreground_set2 <- gsub("T", "U", transite:::ge$foreground2_df$seq)
#' foreground_sets <- list(foreground_set1, foreground_set2)
#' background_set <- gsub("T", "U", transite:::ge$background_df$seq)
#'
#' # run TSMA with all Transite motifs
#' results <- run_kmer_tsma(foreground_sets, background_set)
#'
#' # run TSMA with a subset of Transite motifs
#' results <- run_kmer_tsma(foreground_sets, background_set,
#' motifs = get_motif_by_rbp("ELAVL1"))
#'
#' # run TSMA with user-defined motif
#' toy_motif <- create_kmer_motif(
#' "toy_motif", "example RBP",
#' c("AACCGG", "AAAACG", "AACACG"), "example type", "example species", "user"
#' )
#' results <- run_matrix_tsma(foreground_sets, background_set,
#' motifs = list(toy_motif))
#' }
#'
#' @family TSMA functions
#' @family \emph{k}-mer functions
#' @importFrom stats p.adjust
#' @importFrom dplyr select
#' @importFrom dplyr filter
#' @export
run_kmer_tsma <- function(foreground_sets,
background_set,
motifs = NULL,
k = 6,
fg_permutations = 5000,
kmer_significance_threshold = 0.01,
produce_plot = TRUE,
p_adjust_method = "BH",
p_combining_method = "fisher",
n_cores = 1) {
# avoid CRAN note
origin_sequences <- kmer <- enrichment <- p_value <- adj_p_value <- NULL
if (is.null(motifs)) {
motifs <- get_motifs()
}
enrichment_result <-
calculate_kmer_enrichment(
foreground_sets,
background_set,
k,
p_adjust_method = p_adjust_method,
n_cores = n_cores
)
message("calculated enrichment for all foreground sets")
i <- 1
if (!is.null(enrichment_result)) {
set_sizes <- unique(unlist(lapply(foreground_sets, length)))
random_enrichments <- new.env()
for (set_size in set_sizes) {
if (set_size < 10) {
adapted_fg_permutations <- min(fg_permutations, 100)
} else if (set_size < 30) {
adapted_fg_permutations <- min(fg_permutations, 500)
} else {
adapted_fg_permutations <- fg_permutations
}
assign(
as.character(set_size),
generate_permuted_enrichments(
set_size,
background_set,
k,
n_permutations = adapted_fg_permutations,
n_cores = n_cores
),
envir = random_enrichments
)
}
message("calculated enrichment for all permuted sets")
motif_result <-
lapply(seq_len(length(foreground_sets)), function(i) {
kmers_df <- enrichment_result$dfs[[i]]
kmers_df$kmer <- enrichment_result$kmers
kmers_df$origin_sequences <- as.character(enrichment_result$kmer_origins)
foreground_result <-
lapply(motifs, function(motif) {
if (k == 6) {
rbp_kmers <- get_hexamers(motif)
} else if (k == 7) {
rbp_kmers <- get_heptamers(motif)
}
idx <-
which(enrichment_result$kmers %in% rbp_kmers)
motif_kmers_df <- kmers_df[idx, ]
motif_kmers_df <-
dplyr::select(
motif_kmers_df,
kmer,
enrichment,
p_value,
adj_p_value,
origin_sequences
)
geo_mean <-
geometric_mean(motif_kmers_df$enrichment)
perm_test <-
estimate_significance(
geo_mean,
rbp_kmers,
get(
as.character(length(foreground_sets[[i]])),
envir = random_enrichments,
inherits = FALSE
),
alternative = "two_sided",
conf_level = 0.95,
produce_plot = produce_plot
)
motif_kmers_enriched_df <-
dplyr::filter(motif_kmers_df, enrichment > 1)
enriched_kmers_combined_p_value <-
p_combine(motif_kmers_enriched_df$adj_p_value,
method = p_combining_method
)
motif_kmers_depleted_df <-
dplyr::filter(motif_kmers_df, enrichment < 1)
depleted_kmers_combined_p_value <-
p_combine(motif_kmers_depleted_df$adj_p_value,
method = p_combining_method
)
if (produce_plot) {
volcano_plot <-
draw_volcano_plot(
kmers_df,
rbp_kmers,
paste(get_rbps(motif), collapse = ", "),
kmer_significance_threshold
)
} else {
volcano_plot <- NULL
}
return(
list(
df = list(
motif_id = get_id(motif),
motif_rbps = paste0(get_rbps(motif),
collapse = ", "),
geo_mean_enrichment = geo_mean,
p_value_estimate = perm_test$p_value_estimate,
cont_int_low = perm_test$conf_int[1],
cont_int_high = perm_test$conf_int[2],
enriched_kmers_combined_p_value = enriched_kmers_combined_p_value$p_value,
depleted_kmers_combined_p_value = depleted_kmers_combined_p_value$p_value
),
motif_kmers_df = motif_kmers_df,
volcano_plot = volcano_plot,
perm_test_plot = perm_test$plot,
enriched_kmers_combined_p_value = enriched_kmers_combined_p_value,
depleted_kmers_combined_p_value = depleted_kmers_combined_p_value
)
)
})
df <-
as.data.frame(do.call(
"rbind",
lapply(foreground_result, function(x)
x$df)
), stringsAsFactors = FALSE)
df$motif_id <- as.character(df$motif_id)
df$motif_rbps <- as.character(df$motif_rbps)
df$geo_mean_enrichment <-
as.numeric(df$geo_mean_enrichment)
df$p_value_estimate <-
as.numeric(df$p_value_estimate)
df$cont_int_low <- as.numeric(df$cont_int_low)
df$cont_int_high <- as.numeric(df$cont_int_high)
df$enriched_kmers_combined_p_value <-
as.numeric(df$enriched_kmers_combined_p_value)
df$depleted_kmers_combined_p_value <-
as.numeric(df$depleted_kmers_combined_p_value)
df$adj_p_value_estimate <-
stats::p.adjust(df$p_value_estimate,
method = p_adjust_method)
df$adj_enriched_kmers_combined_p_value <-
stats::p.adjust(df$enriched_kmers_combined_p_value,
method = p_adjust_method)
df$adj_depleted_kmers_combined_p_value <-
stats::p.adjust(df$depleted_kmers_combined_p_value,
method = p_adjust_method)
motif_kmers_dfs <-
lapply(foreground_result, function(x)
x$motif_kmers_df)
volcano_plots <-
lapply(foreground_result, function(x)
x$volcano_plot)
perm_test_plots <-
lapply(foreground_result, function(x)
x$perm_test_plot)
enriched_kmers_combined_p_values <-
lapply(foreground_result, function(x)
x$enriched_kmers_combined_p_value)
depleted_kmers_combined_p_values <-
lapply(foreground_result, function(x)
x$depleted_kmers_combined_p_value)
return(
list(
df = df,
motif_kmers_dfs = motif_kmers_dfs,
volcano_plots = volcano_plots,
perm_test_plots = perm_test_plots,
enriched_kmers_combined_p_values = enriched_kmers_combined_p_values,
depleted_kmers_combined_p_values = depleted_kmers_combined_p_values
)
)
})
result <-
lapply(seq_len(length(foreground_sets)), function(i) {
enrichment_df <- enrichment_result$dfs[[i]]
enrichment_df$kmer <- enrichment_result$kmers
return(
list(
enrichment_df = enrichment_df,
motif_df = motif_result[[i]]$df,
motif_kmers_dfs = motif_result[[i]]$motif_kmers_dfs,
volcano_plots = motif_result[[i]]$volcano_plots,
perm_test_plots = motif_result[[i]]$perm_test_plots,
enriched_kmers_combined_p_values = motif_result[[i]]$enriched_kmers_combined_p_values,
depleted_kmers_combined_p_values = motif_result[[i]]$depleted_kmers_combined_p_values
)
)
})
return(result)
} else {
return(NULL)
}
}
#' @title \emph{k}-mer-based Spectrum Motif Analysis
#'
#' @description
#' SPMA helps to illuminate the relationship between RBP binding evidence
#' and the transcript
#' sorting criterion, e.g., fold change between treatment and control samples.
#'
#' @param sorted_transcript_sequences character vector of ranked sequences,
#' either DNA
#' (only containing upper case characters A, C, G, T) or RNA (A, C, G, U).
#' The sequences in \code{sorted_transcript_sequences} must be
#' ranked (i.e., sorted).
#' Commonly used sorting criteria are measures of differential expression, such
#' as fold change or signal-to-noise ratio (e.g., between treatment and control
#' samples in gene expression profiling experiments).
#'
#' @inheritParams run_kmer_tsma
#' @inheritParams subdivide_data
#' @inheritParams score_spectrum
#'
#' @return A list with the following components:
#' \tabular{rl}{
#' \code{foreground_scores} \tab the result of \code{\link{run_kmer_tsma}}
#' for the binned data\cr
#' \code{spectrum_info_df} \tab a data frame with the SPMA results\cr
#' \code{spectrum_plots} \tab a list of spectrum plots, as generated by
#' \code{\link{score_spectrum}}\cr
#' \code{classifier_scores} \tab a list of classifier scores, as returned by
#' \code{\link{classify_spectrum}}
#' }
#'
#' @details
#' In order to investigate how motif targets are distributed across a
#' spectrum of
#' transcripts (e.g., all transcripts of a platform, ordered by fold change),
#' Spectrum Motif Analysis visualizes the gradient of RBP binding evidence
#' across all transcripts.
#'
#' The \emph{k}-mer-based approach differs from the matrix-based approach by
#' how the sequences are
#' scored. Here, sequences are broken into \emph{k}-mers, i.e.,
#' oligonucleotide sequences of
#' \emph{k} bases.
#' And only statistically significantly enriched or depleted \emph{k}-mers
#' are then used to
#' calculate a score for each RNA-binding protein, which quantifies its
#' target overrepresentation.
#'
#' @examples
#' # example data set
#' background_df <- transite:::ge$background_df
#' # sort sequences by signal-to-noise ratio
#' background_df <- dplyr::arrange(background_df, value)
#' # character vector of named and ranked (by signal-to-noise ratio) sequences
#' background_seqs <- gsub("T", "U", background_df$seq)
#' names(background_seqs) <- paste0(background_df$refseq, "|",
#' background_df$seq_type)
#'
#' results <- run_kmer_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "signal-to-noise ratio",
#' motifs = get_motif_by_id("M178_0.6"),
#' n_bins = 20,
#' fg_permutations = 10)
#'
#' \dontrun{
#' results <- run_kmer_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "signal-to-noise ratio")}
#'
#' @family SPMA functions
#' @family \emph{k}-mer functions
#' @importFrom stats p.adjust
#' @importFrom dplyr select
#' @importFrom dplyr filter
#' @export
run_kmer_spma <- function(sorted_transcript_sequences,
sorted_transcript_values = NULL,
transcript_values_label = "transcript value",
motifs = NULL,
k = 6,
n_bins = 40,
midpoint = 0,
x_value_limits = NULL,
max_model_degree = 1,
max_cs_permutations = 10000000,
min_cs_permutations = 5000,
fg_permutations = 5000,
p_adjust_method = "BH",
p_combining_method = "fisher",
n_cores = 1) {
# avoid CRAN note
motif_id <-
motif_rbps <-
adj_r_squared <- degree <- residuals <- slope <- NULL
f_statistic <-
f_statistic_p_value <- f_statistic_adj_p_value <- NULL
consistency_score <-
consistency_score_p_value <-
consistency_score_adj_p_value <- NULL
consistency_score_n <- aggregate_classifier_score <- NULL
n_significant <-
n_very_significant <- n_extremely_significant <- NULL
foreground_sets <- subdivide_data(sorted_transcript_sequences, n_bins)
results <- run_kmer_tsma(
foreground_sets,
sorted_transcript_sequences,
motifs = motifs,
k = k,
fg_permutations = fg_permutations,
kmer_significance_threshold = 0.01,
produce_plot = FALSE,
p_adjust_method = p_adjust_method,
p_combining_method = p_combining_method,
n_cores = n_cores
)
if (length(results) > 0) {
dfs <- lapply(results, function(result) {
result$motif_df
})
enrichment_df <- do.call("rbind", dfs)
enrichment_df$adj_p_value_estimate <-
stats::p.adjust(enrichment_df$p_value_estimate,
method = p_adjust_method
)
if (is.null(motifs)) {
motifs <- get_motifs()
}
spectrum_info <- lapply(motifs, function(motif) {
motif_data_df <- dplyr::filter(enrichment_df,
motif_id == get_id(motif))
values <- motif_data_df$geo_mean_enrichment
values[values == 0] <-
0.01 # avoid -Inf after taking the log
score <-
score_spectrum(
log(values),
p_values = motif_data_df$adj_p_value_estimate,
sorted_transcript_values = sorted_transcript_values,
transcript_values_label = transcript_values_label,
midpoint = midpoint,
x_value_limits = x_value_limits,
max_model_degree = max_model_degree,
max_cs_permutations = max_cs_permutations,
min_cs_permutations = min_cs_permutations
)
n_significant <-
sum(motif_data_df$adj_p_value_estimate <= 0.05)
classifier_score <-
classify_spectrum(
get_adj_r_squared(score),
get_model_degree(score),
get_model_slope(score),
get_consistency_score_n(score),
n_significant,
n_bins
)
return(
list(
info = list(
motif_id = get_id(motif),
motif_rbps = paste(get_rbps(motif), collapse = ", "),
adj_r_squared = get_adj_r_squared(score),
degree = get_model_degree(score),
residuals = get_model_residuals(score),
slope = get_model_slope(score),
f_statistic = get_model_f_statistic(score),
f_statistic_p_value = get_model_f_statistic_p_value(score),
consistency_score = get_consistency_score(score),
consistency_score_p_value = get_consistency_score_p_value(score),
consistency_score_n = get_consistency_score_n(score),
n_significant = n_significant,
n_very_significant = sum(motif_data_df$adj_p_value <= 0.01),
n_extremely_significant = sum(motif_data_df$adj_p_value <= 0.001),
aggregate_classifier_score = sum(classifier_score)
),
spectrum_plot = score@plot,
classifier_score = classifier_score
)
)
})
spectrum_info_df <-
as.data.frame(do.call("rbind", lapply(spectrum_info, function(x)
x$info)),
stringsAsFactors = FALSE
)
spectrum_info_df$motif_id <-
as.character(spectrum_info_df$motif_id)
spectrum_info_df$motif_rbps <-
as.character(spectrum_info_df$motif_rbps)
spectrum_info_df$adj_r_squared <-
as.numeric(spectrum_info_df$adj_r_squared)
spectrum_info_df$degree <-
as.integer(spectrum_info_df$degree)
spectrum_info_df$residuals <-
as.numeric(spectrum_info_df$residuals)
spectrum_info_df$slope <-
as.numeric(spectrum_info_df$slope)
spectrum_info_df$f_statistic <-
as.numeric(spectrum_info_df$f_statistic)
spectrum_info_df$f_statistic_p_value <-
as.numeric(spectrum_info_df$f_statistic_p_value)
spectrum_info_df$consistency_score <-
as.numeric(spectrum_info_df$consistency_score)
spectrum_info_df$consistency_score_p_value <-
as.numeric(spectrum_info_df$consistency_score_p_value)
spectrum_info_df$consistency_score_n <-
as.integer(spectrum_info_df$consistency_score_n)
spectrum_info_df$n_significant <-
as.integer(spectrum_info_df$n_significant)
spectrum_info_df$n_very_significant <-
as.integer(spectrum_info_df$n_very_significant)
spectrum_info_df$n_extremely_significant <-
as.integer(spectrum_info_df$n_extremely_significant)
spectrum_info_df$aggregate_classifier_score <-
as.integer(spectrum_info_df$aggregate_classifier_score)
spectrum_info_df$f_statistic_adj_p_value <-
stats::p.adjust(spectrum_info_df$f_statistic_p_value,
method = p_adjust_method)
spectrum_info_df$consistency_score_adj_p_value <-
stats::p.adjust(spectrum_info_df$consistency_score_p_value,
method = p_adjust_method)
spectrum_info_df <-
dplyr::select(
spectrum_info_df,
motif_id,
motif_rbps,
adj_r_squared,
degree,
residuals,
slope,
f_statistic,
f_statistic_p_value,
f_statistic_adj_p_value,
consistency_score,
consistency_score_p_value,
consistency_score_adj_p_value,
consistency_score_n,
n_significant,
n_very_significant,
n_extremely_significant,
aggregate_classifier_score
)
spectrum_plots <-
lapply(spectrum_info, function(x)
x$spectrum_plot)
classifier_scores <-
lapply(spectrum_info, function(x)
x$classifier_score)
} else {
stop("empty foreground sets")
}
return(
list(
foreground_scores = results,
spectrum_info_df = spectrum_info_df,
spectrum_plots = spectrum_plots,
classifier_scores = classifier_scores
)
)
}
kkrismer/transite documentation built on July 13, 2024, 8:01 a.m.
R Package Documentation
Browse R Packages
We want your feedback!
Note that we can't provide technical support on individual packages. You should contact the package authors for that.
Defines functions run_kmer_spma run_kmer_tsma run_matrix_spma run_matrix_tsma
Documented in run_kmer_spma run_kmer_tsma run_matrix_spma run_matrix_tsma
#' @title Matrix-based Transcript Set Motif Analysis
#'
#' @description
#' Calculates motif enrichment in foreground sets versus a background
#' set using position
#' weight matrices to identify putative binding sites
#'
#' @param foreground_sets a list of named character vectors of
#' foreground sequences
#' (only containing upper case characters A, C, G, T), where the
#' names are RefSeq identifiers
#' and sequence
#' type qualifiers (\code{"3UTR"}, \code{"5UTR"}, \code{"mRNA"}), e.g.
#' \code{"NM_010356|3UTR"}. Names are only used to cache results.
#' @param background_set a named character vector of background
#' sequences (naming follows same
#' rules as foreground set sequences)
#' @inheritParams score_transcripts
#' @inheritParams calculate_motif_enrichment
#'
#' @return A list with the following components:
#' \tabular{rl}{
#' \code{foreground_scores} \tab the result of \code{\link{score_transcripts}}
#' for the foreground
#' sets\cr
#' \code{background_scores} \tab the result of \code{\link{score_transcripts}}
#' for the background
#' set\cr
#' \code{enrichment_dfs} \tab a list of data frames, returned by
#' \code{\link{calculate_motif_enrichment}}
#' }
#'
#' @details
#' Motif transcript set analysis can be used to identify RNA binding proteins,
#' whose targets are
#' significantly overrepresented or underrepresented in certain sets of
#' transcripts.
#'
#' The aim of Transcript Set Motif Analysis (TSMA) is to identify the
#' overrepresentation
#' and underrepresentation of potential RBP targets (binding sites)
#' in a set (or sets) of
#' sequences, i.e., the foreground set, relative to the entire population
#' of sequences.
#' The latter is called background set, which can be composed of all
#' sequences of the genes
#' of a microarray platform or all sequences of an organism or any
#' other meaningful
#' superset of the foreground sets.
#'
#' The matrix-based approach skips the \emph{k}-merization step of
#' the \emph{k}-mer-based approach
#' and instead scores the transcript sequence as a whole with a
#' position specific scoring matrix.
#'
#' For each sequence in foreground and background sets and each
#' sequence motif,
#' the scoring algorithm evaluates the score for each sequence position.
#' Positions with
#' a relative score greater than a certain threshold are considered hits, i.e.,
#' putative binding sites.
#'
#' By scoring all sequences in foreground and background sets, a hit count
#' for each motif and
#' each set is obtained, which is used to calculate enrichment values and
#' associated p-values
#' in the same way in which motif-compatible hexamer enrichment values are
#' calculated in
#' the k -mer-based approach. P-values are adjusted with one of the available
#' adjustment methods.
#'
#' An advantage of the matrix-based approach is the possibility of detecting
#' clusters of
#' binding sites. This can be done by counting regions with many hits using
#' positional
#' hit information or by simply applying a hit count threshold per sequence,
#' e.g., only
#' sequences with more than some number of hits are considered. Homotypic
#' clusters of RBP
#' binding sites may play a similar role as clusters of transcription factors.
#'
#' @examples
#' # define simple sequence sets for foreground and background
#' foreground_set1 <- c(
#' "CAACAGCCUUAAUU", "CAGUCAAGACUCC", "CUUUGGGGAAU",
#' "UCAUUUUAUUAAA", "AAUUGGUGUCUGGAUACUUCCCUGUACAU",
#' "AUCAAAUUA", "AGAU", "GACACUUAAAGAUCCU",
#' "UAGCAUUAACUUAAUG", "AUGGA", "GAAGAGUGCUCA",
#' "AUAGAC", "AGUUC", "CCAGUAA"
#' )
#' names(foreground_set1) <- c(
#' "NM_1_DUMMY|3UTR", "NM_2_DUMMY|3UTR", "NM_3_DUMMY|3UTR",
#' "NM_4_DUMMY|3UTR", "NM_5_DUMMY|3UTR", "NM_6_DUMMY|3UTR",
#' "NM_7_DUMMY|3UTR",
#' "NM_8_DUMMY|3UTR", "NM_9_DUMMY|3UTR", "NM_10_DUMMY|3UTR",
#' "NM_11_DUMMY|3UTR",
#' "NM_12_DUMMY|3UTR", "NM_13_DUMMY|3UTR", "NM_14_DUMMY|3UTR"
#' )
#'
#' foreground_set2 <- c("UUAUUUA", "AUCCUUUACA", "UUUUUUU", "UUUCAUCAUU")
#' names(foreground_set2) <- c(
#' "NM_15_DUMMY|3UTR", "NM_16_DUMMY|3UTR", "NM_17_DUMMY|3UTR",
#' "NM_18_DUMMY|3UTR"
#' )
#'
#' foreground_sets <- list(foreground_set1, foreground_set2)
#'
#' background_set <- c(
#' "CAACAGCCUUAAUU", "CAGUCAAGACUCC", "CUUUGGGGAAU",
#' "UCAUUUUAUUAAA", "AAUUGGUGUCUGGAUACUUCCCUGUACAU",
#' "AUCAAAUUA", "AGAU", "GACACUUAAAGAUCCU",
#' "UAGCAUUAACUUAAUG", "AUGGA", "GAAGAGUGCUCA",
#' "AUAGAC", "AGUUC", "CCAGUAA",
#' "UUAUUUA", "AUCCUUUACA", "UUUUUUU", "UUUCAUCAUU",
#' "CCACACAC", "CUCAUUGGAG", "ACUUUGGGACA", "CAGGUCAGCA"
#' )
#' names(background_set) <- c(
#' "NM_1_DUMMY|3UTR", "NM_2_DUMMY|3UTR", "NM_3_DUMMY|3UTR",
#' "NM_4_DUMMY|3UTR", "NM_5_DUMMY|3UTR", "NM_6_DUMMY|3UTR",
#' "NM_7_DUMMY|3UTR",
#' "NM_8_DUMMY|3UTR", "NM_9_DUMMY|3UTR", "NM_10_DUMMY|3UTR",
#' "NM_11_DUMMY|3UTR",
#' "NM_12_DUMMY|3UTR", "NM_13_DUMMY|3UTR", "NM_14_DUMMY|3UTR",
#' "NM_15_DUMMY|3UTR",
#' "NM_16_DUMMY|3UTR", "NM_17_DUMMY|3UTR", "NM_18_DUMMY|3UTR",
#' "NM_19_DUMMY|3UTR",
#' "NM_20_DUMMY|3UTR", "NM_21_DUMMY|3UTR", "NM_22_DUMMY|3UTR"
#' )
#'
#' # run cached version of TSMA with all Transite motifs (recommended):
#' # results <- run_matrix_tsma(foreground_sets, background_set)
#'
#' # run uncached version with one motif:
#' motif_db <- get_motif_by_id("M178_0.6")
#' results <- run_matrix_tsma(foreground_sets, background_set, motifs = motif_db,
#' cache = FALSE)
#'
#' \dontrun{
#' # define example sequence sets for foreground and background
#' foreground1_df <- transite:::ge$foreground1_df
#' foreground_set1 <- gsub("T", "U", foreground1_df$seq)
#' names(foreground_set1) <- paste0(foreground1_df$refseq, "|",
#' foreground1_df$seq_type)
#'
#' foreground2_df <- transite:::ge$foreground2_df
#' foreground_set2 <- gsub("T", "U", foreground2_df$seq)
#' names(foreground_set2) <- paste0(foreground2_df$refseq, "|",
#' foreground2_df$seq_type)
#'
#' foreground_sets <- list(foreground_set1, foreground_set2)
#'
#' background_df <- transite:::ge$background_df
#' background_set <- gsub("T", "U", background_df$seq)
#' names(background_set) <- paste0(background_df$refseq, "|",
#' background_df$seq_type)
#'
#' # run cached version of TSMA with all Transite motifs (recommended)
#' results <- run_matrix_tsma(foreground_sets, background_set)
#'
#' # run uncached version of TSMA with all Transite motifs
#' results <- run_matrix_tsma(foreground_sets, background_set, cache = FALSE)
#'
#' # run TSMA with a subset of Transite motifs
#' results <- run_matrix_tsma(foreground_sets, background_set,
#' motifs = get_motif_by_rbp("ELAVL1"))
#'
#' # run TSMA with user-defined motif
#' toy_motif <- create_matrix_motif(
#' "toy_motif", "example RBP", toy_motif_matrix,
#' "example type", "example species", "user"
#' )
#' results <- run_matrix_tsma(foreground_sets, background_set,
#' motifs = list(toy_motif))
#' }
#'
#' @family TSMA functions
#' @family matrix functions
#' @importFrom dplyr arrange
#' @export
run_matrix_tsma <- function(foreground_sets,
background_set,
motifs = NULL,
max_hits = 5,
threshold_method = "p_value",
threshold_value = 0.25^6,
max_fg_permutations = 1000000,
min_fg_permutations = 1000,
e = 5,
p_adjust_method = "BH",
n_cores = 1,
cache = paste0(tempdir(), "/sc/")) {
# avoid CRAN note
adj_p_value <- p_value <- NULL
i <- 1
foreground_scores <-
lapply(foreground_sets, function(foreground_set) {
result <-
score_transcripts(
foreground_set,
motifs = motifs,
max_hits = max_hits,
threshold_method = threshold_method,
threshold_value = threshold_value,
n_cores = n_cores,
cache = cache
)
message(paste0("scored transcripts in foreground set ", i))
i <<- i + 1
return(result)
})
background_scores <-
score_transcripts(
background_set,
motifs = motifs,
max_hits = max_hits,
threshold_method = threshold_method,
threshold_value = threshold_value,
n_cores = n_cores,
cache = cache
)
message("scored transcripts in background set")
i <- 1
enrichment_dfs <-
lapply(foreground_scores, function(scores_per_condition) {
enrichment_df <-
calculate_motif_enrichment(
scores_per_condition$df,
background_scores$df,
background_scores$total_sites,
background_scores$absolute_hits,
length(foreground_sets[[i]]),
max_fg_permutations = max_fg_permutations,
min_fg_permutations = min_fg_permutations,
e = e,
p_adjust_method = p_adjust_method
)
enrichment_df <-
dplyr::arrange(enrichment_df, adj_p_value, p_value)
message(paste0("calculated enrichment for foreground set ", i))
i <<- i + 1
return(enrichment_df)
})
return(
list(
foreground_scores = foreground_scores,
background_scores = background_scores,
enrichment_dfs = enrichment_dfs
)
)
}
#' @title Matrix-based Spectrum Motif Analysis
#'
#' @description
#' SPMA helps to illuminate the relationship between RBP binding
#' evidence and the transcript
#' sorting criterion, e.g., fold change between treatment and control samples.
#'
#' @param sorted_transcript_sequences named character vector of ranked sequences
#' (only containing upper case characters A, C, G, T), where the
#' names are RefSeq identifiers and sequence
#' type qualifiers (\code{"3UTR"}, \code{"5UTR"} or \code{"mRNA"}), separated by
#' \code{"|"}, e.g.
#' \code{"NM_010356|3UTR"}. Names are only used to cache results.
#' The sequences in \code{sorted_transcript_sequences} must be ranked
#' (i.e., sorted).
#' Commonly used sorting criteria are measures of differential expression, such
#' as fold change or signal-to-noise ratio (e.g., between treatment and control
#' samples in gene expression profiling experiments).
#' @inheritParams run_matrix_tsma
#' @inheritParams subdivide_data
#' @inheritParams score_spectrum
#'
#' @return A list with the following components:
#' \tabular{rl}{
#' \code{foreground_scores} \tab the result of \code{\link{score_transcripts}}
#' for the foreground
#' sets (the bins)\cr
#' \code{background_scores} \tab the result of \code{\link{score_transcripts}}
#' for the background
#' set\cr
#' \code{enrichment_dfs} \tab a list of data frames, returned by
#' \code{\link{calculate_motif_enrichment}}\cr
#' \code{spectrum_info_df} \tab a data frame with the SPMA results\cr
#' \code{spectrum_plots} \tab a list of spectrum plots, as generated by
#' \code{\link{score_spectrum}}\cr
#' \code{classifier_scores} \tab a list of classifier scores, as returned by
#' \code{\link{classify_spectrum}}
#' }
#'
#' @details
#' In order to investigate how motif targets are distributed across a
#' spectrum of
#' transcripts (e.g., all transcripts of a platform, ordered by fold change),
#' Spectrum Motif Analysis visualizes the gradient of RBP binding evidence
#' across all transcripts.
#'
#' The matrix-based approach skips the \emph{k}-merization step of the
#' \emph{k}-mer-based approach
#' and instead scores the transcript sequence as a whole with a position
#' specific scoring matrix.
#'
#' For each sequence in foreground and background sets and each sequence motif,
#' the scoring algorithm evaluates the score for each sequence position.
#' Positions with
#' a relative score greater than a certain threshold are considered hits, i.e.,
#' putative binding sites.
#'
#' By scoring all sequences in foreground and background sets, a hit count
#' for each motif and
#' each set is obtained, which is used to calculate enrichment values and
#' associated p-values
#' in the same way in which motif-compatible hexamer enrichment values are
#' calculated in
#' the \emph{k}-mer-based approach. P-values are adjusted with one of the
#' available adjustment methods.
#'
#' An advantage of the matrix-based approach is the possibility of detecting
#' clusters of
#' binding sites. This can be done by counting regions with many hits using
#' positional
#' hit information or by simply applying a hit count threshold per
#' sequence, e.g., only
#' sequences with more than some number of hits are considered. Homotypic
#' clusters of RBP
#' binding sites may play a similar role as clusters of transcription factors.
#'
#' @examples
#' # example data set
#' background_df <- transite:::ge$background_df
#' # sort sequences by signal-to-noise ratio
#' background_df <- dplyr::arrange(background_df, value)
#' # character vector of named and ranked (by signal-to-noise ratio) sequences
#' background_seqs <- gsub("T", "U", background_df$seq)
#' names(background_seqs) <- paste0(background_df$refseq, "|",
#' background_df$seq_type)
#'
#' results <- run_matrix_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "signal-to-noise ratio",
#' motifs = get_motif_by_id("M178_0.6"),
#' n_bins = 20,
#' max_fg_permutations = 10000)
#'
#' \dontrun{
#' results <- run_matrix_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "SNR") }
#'
#' @family SPMA functions
#' @family matrix functions
#' @importFrom stats p.adjust
#' @importFrom dplyr filter
#' @export
run_matrix_spma <- function(sorted_transcript_sequences,
sorted_transcript_values = NULL,
transcript_values_label = "transcript value",
motifs = NULL,
n_bins = 40,
midpoint = 0,
x_value_limits = NULL,
max_model_degree = 1,
max_cs_permutations = 10000000,
min_cs_permutations = 5000,
max_hits = 5,
threshold_method = "p_value",
threshold_value = 0.25^6,
max_fg_permutations = 1000000,
min_fg_permutations = 1000,
e = 5,
p_adjust_method = "BH",
n_cores = 1,
cache = paste0(tempdir(), "/sc/")) {
# avoid CRAN note
motif_id <- motif_rbps <- adj_r_squared <- degree <-
residuals <- slope <- NULL
f_statistic <- f_statistic_p_value <- f_statistic_adj_p_value <- NULL
consistency_score <-
consistency_score_p_value <-
consistency_score_adj_p_value <-
consistency_score_n <- NULL
n_significant <-
n_very_significant <-
n_extremely_significant <-
aggregate_classifier_score <- NULL
foreground_sets <- subdivide_data(sorted_transcript_sequences, n_bins)
results <- run_matrix_tsma(
foreground_sets,
sorted_transcript_sequences,
motifs = motifs,
max_hits = max_hits,
threshold_method = threshold_method,
threshold_value = threshold_value,
max_fg_permutations = max_fg_permutations,
min_fg_permutations = min_fg_permutations,
e = e,
p_adjust_method = p_adjust_method,
n_cores = n_cores,
cache = cache
)
if (length(results$enrichment_dfs) > 0) {
enrichment_df <- do.call("rbind", results$enrichment_dfs)
enrichment_df$adj_p_value <-
stats::p.adjust(enrichment_df$p_value, method = p_adjust_method)
if (is.null(motifs)) {
motifs <- get_motifs()
}
spectrum_info <- lapply(motifs, function(motif) {
motif_data_df <- dplyr::filter(enrichment_df,
motif_id == get_id(motif))
values <- motif_data_df$enrichment
values[values == 0] <-
0.01 # avoid -Inf after taking the log
score <-
score_spectrum(
log(values),
p_values = motif_data_df$adj_p_value,
sorted_transcript_values = sorted_transcript_values,
transcript_values_label = transcript_values_label,
midpoint = midpoint,
x_value_limits = x_value_limits,
max_model_degree = max_model_degree,
max_cs_permutations = max_cs_permutations,
min_cs_permutations = min_cs_permutations
)
n_significant <-
sum(motif_data_df$adj_p_value <= 0.05)
classifier_score <-
classify_spectrum(
get_adj_r_squared(score),
get_model_degree(score),
get_model_slope(score),
get_consistency_score_n(score),
n_significant,
n_bins
)
return(
list(
info = list(
motif_id = get_id(motif),
motif_rbps = paste(get_rbps(motif), collapse = ", "),
adj_r_squared = get_adj_r_squared(score),
degree = get_model_degree(score),
residuals = get_model_residuals(score),
slope = get_model_slope(score),
f_statistic = get_model_f_statistic(score),
f_statistic_p_value = get_model_f_statistic_p_value(score),
consistency_score = get_consistency_score(score),
consistency_score_p_value = get_consistency_score_p_value(score),
consistency_score_n = get_consistency_score_n(score),
n_significant = n_significant,
n_very_significant = sum(motif_data_df$adj_p_value <= 0.01),
n_extremely_significant = sum(motif_data_df$adj_p_value <= 0.001),
aggregate_classifier_score = sum(classifier_score)
),
spectrum_plot = score@plot,
classifier_score = classifier_score
)
)
})
spectrum_info_df <-
as.data.frame(do.call("rbind", lapply(spectrum_info, function(x)
x$info)),
stringsAsFactors = FALSE
)
spectrum_info_df$motif_id <-
as.character(spectrum_info_df$motif_id)
spectrum_info_df$motif_rbps <-
as.character(spectrum_info_df$motif_rbps)
spectrum_info_df$adj_r_squared <-
as.numeric(spectrum_info_df$adj_r_squared)
spectrum_info_df$degree <-
as.integer(spectrum_info_df$degree)
spectrum_info_df$residuals <-
as.numeric(spectrum_info_df$residuals)
spectrum_info_df$slope <-
as.numeric(spectrum_info_df$slope)
spectrum_info_df$f_statistic <-
as.numeric(spectrum_info_df$f_statistic)
spectrum_info_df$f_statistic_p_value <-
as.numeric(spectrum_info_df$f_statistic_p_value)
spectrum_info_df$consistency_score <-
as.numeric(spectrum_info_df$consistency_score)
spectrum_info_df$consistency_score_p_value <-
as.numeric(spectrum_info_df$consistency_score_p_value)
spectrum_info_df$consistency_score_n <-
as.integer(spectrum_info_df$consistency_score_n)
spectrum_info_df$n_significant <-
as.integer(spectrum_info_df$n_significant)
spectrum_info_df$n_very_significant <-
as.integer(spectrum_info_df$n_very_significant)
spectrum_info_df$n_extremely_significant <-
as.integer(spectrum_info_df$n_extremely_significant)
spectrum_info_df$aggregate_classifier_score <-
as.integer(spectrum_info_df$aggregate_classifier_score)
spectrum_info_df$f_statistic_adj_p_value <-
stats::p.adjust(spectrum_info_df$f_statistic_p_value,
method = p_adjust_method)
spectrum_info_df$consistency_score_adj_p_value <-
stats::p.adjust(spectrum_info_df$consistency_score_p_value,
method = p_adjust_method)
spectrum_info_df <-
dplyr::select(
spectrum_info_df,
motif_id,
motif_rbps,
adj_r_squared,
degree,
residuals,
slope,
f_statistic,
f_statistic_p_value,
f_statistic_adj_p_value,
consistency_score,
consistency_score_p_value,
consistency_score_adj_p_value,
consistency_score_n,
n_significant,
n_very_significant,
n_extremely_significant,
aggregate_classifier_score
)
spectrum_plots <-
lapply(spectrum_info, function(x)
x$spectrum_plot)
classifier_scores <-
lapply(spectrum_info, function(x)
x$classifier_score)
} else {
stop("empty foreground sets")
}
return(
list(
foreground_scores = results$foreground_scores,
background_scores = results$background_scores,
enrichment_dfs = results$enrichment_dfs,
spectrum_info_df = spectrum_info_df,
spectrum_plots = spectrum_plots,
classifier_scores = classifier_scores
)
)
}
#' @title \emph{k}-mer-based Transcript Set Motif Analysis
#'
#' @description
#' Calculates the enrichment of putative binding sites in foreground sets
#' versus a background set
#' using \emph{k}-mers to identify putative binding sites
#'
#' @param motifs a list of motifs that is used to score the specified sequences.
#' If \code{is.null(motifs)} then all Transite motifs are used.
#' @param fg_permutations numer of foreground permutations
#' @param kmer_significance_threshold p-value threshold for significance,
#' e.g., \code{0.05} or
#' \code{0.01} (used for volcano plots)
#' @param produce_plot if \code{TRUE} volcano plots and distribution plots
#' are created
#' @param p_combining_method one of the following: Fisher (1932)
#' (\code{"fisher"}), Stouffer (1949),
#' Liptak (1958) (\code{"SL"}), Mudholkar and George (1979)
#' (\code{"MG"}), and Tippett (1931)
#' (\code{"tippett"}) (see \code{\link{p_combine}})
#' @inheritParams calculate_kmer_enrichment
#'
#' @return A list of lists (one for each transcript set) with the
#' following components:
#' \tabular{rl}{
#' \code{enrichment_df} \tab the result of
#' \code{\link{compute_kmer_enrichment}} \cr
#' \code{motif_df} \tab \cr
#' \code{motif_kmers_dfs} \tab \cr
#' \code{volcano_plots} \tab volcano plots for each
#' motif (see \code{\link{draw_volcano_plot}}) \cr
#' \code{perm_test_plots} \tab plots of the empirical distribution of
#' \emph{k}-mer enrichment values for each motif \cr
#' \code{enriched_kmers_combined_p_values} \tab \cr
#' \code{depleted_kmers_combined_p_values} \tab
#' }
#'
#' @details
#' Motif transcript set analysis can be used to identify RNA binding
#' proteins, whose targets are
#' significantly overrepresented or underrepresented in certain sets
#' of transcripts.
#'
#' The aim of Transcript Set Motif Analysis (TSMA) is to identify the
#' overrepresentation
#' and underrepresentation of potential RBP targets (binding sites)
#' in a set (or sets) of
#' sequences, i.e., the foreground set, relative to the entire population
#' of sequences.
#' The latter is called background set, which can be composed of all
#' sequences of the genes
#' of a microarray platform or all sequences of an organism or any
#' other meaningful
#' superset of the foreground sets.
#'
#' The \emph{k}-mer-based approach breaks the sequences of foreground
#' and background sets into
#' \emph{k}-mers and calculates the enrichment on a \emph{k}-mer level.
#' In this case, motifs are
#' not represented as position weight matrices, but as lists of \emph{k}-mers.
#'
#' Statistically significantly enriched or depleted \emph{k}-mers
#' are then used to
#' calculate a score for each RNA-binding protein, which quantifies its
#' target overrepresentation.
#'
#' @examples
#' # define simple sequence sets for foreground and background
#' foreground_set1 <- c(
#' "CAACAGCCUUAAUU", "CAGUCAAGACUCC", "CUUUGGGGAAU",
#' "UCAUUUUAUUAAA", "AAUUGGUGUCUGGAUACUUCCCUGUACAU",
#' "AUCAAAUUA", "AGAU", "GACACUUAAAGAUCCU",
#' "UAGCAUUAACUUAAUG", "AUGGA", "GAAGAGUGCUCA",
#' "AUAGAC", "AGUUC", "CCAGUAA"
#' )
#' foreground_set2 <- c("UUAUUUA", "AUCCUUUACA", "UUUUUUU", "UUUCAUCAUU")
#' foreground_sets <- list(foreground_set1, foreground_set2)
#' background_set <- unique(c(foreground_set1, foreground_set2, c(
#' "CCACACAC", "CUCAUUGGAG", "ACUUUGGGACA", "CAGGUCAGCA",
#' "CCACACCGG", "GUCAUCAGU", "GUCAGUCC", "CAGGUCAGGGGCA"
#' )))
#'
#' # run k-mer based TSMA with all Transite motifs (recommended):
#' # results <- run_kmer_tsma(foreground_sets, background_set)
#'
#' # run TSMA with one motif:
#' motif_db <- get_motif_by_id("M178_0.6")
#' results <- run_kmer_tsma(foreground_sets, background_set, motifs = motif_db)
#' \dontrun{
#' # define example sequence sets for foreground and background
#' foreground_set1 <- gsub("T", "U", transite:::ge$foreground1_df$seq)
#' foreground_set2 <- gsub("T", "U", transite:::ge$foreground2_df$seq)
#' foreground_sets <- list(foreground_set1, foreground_set2)
#' background_set <- gsub("T", "U", transite:::ge$background_df$seq)
#'
#' # run TSMA with all Transite motifs
#' results <- run_kmer_tsma(foreground_sets, background_set)
#'
#' # run TSMA with a subset of Transite motifs
#' results <- run_kmer_tsma(foreground_sets, background_set,
#' motifs = get_motif_by_rbp("ELAVL1"))
#'
#' # run TSMA with user-defined motif
#' toy_motif <- create_kmer_motif(
#' "toy_motif", "example RBP",
#' c("AACCGG", "AAAACG", "AACACG"), "example type", "example species", "user"
#' )
#' results <- run_matrix_tsma(foreground_sets, background_set,
#' motifs = list(toy_motif))
#' }
#'
#' @family TSMA functions
#' @family \emph{k}-mer functions
#' @importFrom stats p.adjust
#' @importFrom dplyr select
#' @importFrom dplyr filter
#' @export
run_kmer_tsma <- function(foreground_sets,
background_set,
motifs = NULL,
k = 6,
fg_permutations = 5000,
kmer_significance_threshold = 0.01,
produce_plot = TRUE,
p_adjust_method = "BH",
p_combining_method = "fisher",
n_cores = 1) {
# avoid CRAN note
origin_sequences <- kmer <- enrichment <- p_value <- adj_p_value <- NULL
if (is.null(motifs)) {
motifs <- get_motifs()
}
enrichment_result <-
calculate_kmer_enrichment(
foreground_sets,
background_set,
k,
p_adjust_method = p_adjust_method,
n_cores = n_cores
)
message("calculated enrichment for all foreground sets")
i <- 1
if (!is.null(enrichment_result)) {
set_sizes <- unique(unlist(lapply(foreground_sets, length)))
random_enrichments <- new.env()
for (set_size in set_sizes) {
if (set_size < 10) {
adapted_fg_permutations <- min(fg_permutations, 100)
} else if (set_size < 30) {
adapted_fg_permutations <- min(fg_permutations, 500)
} else {
adapted_fg_permutations <- fg_permutations
}
assign(
as.character(set_size),
generate_permuted_enrichments(
set_size,
background_set,
k,
n_permutations = adapted_fg_permutations,
n_cores = n_cores
),
envir = random_enrichments
)
}
message("calculated enrichment for all permuted sets")
motif_result <-
lapply(seq_len(length(foreground_sets)), function(i) {
kmers_df <- enrichment_result$dfs[[i]]
kmers_df$kmer <- enrichment_result$kmers
kmers_df$origin_sequences <- as.character(enrichment_result$kmer_origins)
foreground_result <-
lapply(motifs, function(motif) {
if (k == 6) {
rbp_kmers <- get_hexamers(motif)
} else if (k == 7) {
rbp_kmers <- get_heptamers(motif)
}
idx <-
which(enrichment_result$kmers %in% rbp_kmers)
motif_kmers_df <- kmers_df[idx, ]
motif_kmers_df <-
dplyr::select(
motif_kmers_df,
kmer,
enrichment,
p_value,
adj_p_value,
origin_sequences
)
geo_mean <-
geometric_mean(motif_kmers_df$enrichment)
perm_test <-
estimate_significance(
geo_mean,
rbp_kmers,
get(
as.character(length(foreground_sets[[i]])),
envir = random_enrichments,
inherits = FALSE
),
alternative = "two_sided",
conf_level = 0.95,
produce_plot = produce_plot
)
motif_kmers_enriched_df <-
dplyr::filter(motif_kmers_df, enrichment > 1)
enriched_kmers_combined_p_value <-
p_combine(motif_kmers_enriched_df$adj_p_value,
method = p_combining_method
)
motif_kmers_depleted_df <-
dplyr::filter(motif_kmers_df, enrichment < 1)
depleted_kmers_combined_p_value <-
p_combine(motif_kmers_depleted_df$adj_p_value,
method = p_combining_method
)
if (produce_plot) {
volcano_plot <-
draw_volcano_plot(
kmers_df,
rbp_kmers,
paste(get_rbps(motif), collapse = ", "),
kmer_significance_threshold
)
} else {
volcano_plot <- NULL
}
return(
list(
df = list(
motif_id = get_id(motif),
motif_rbps = paste0(get_rbps(motif),
collapse = ", "),
geo_mean_enrichment = geo_mean,
p_value_estimate = perm_test$p_value_estimate,
cont_int_low = perm_test$conf_int[1],
cont_int_high = perm_test$conf_int[2],
enriched_kmers_combined_p_value = enriched_kmers_combined_p_value$p_value,
depleted_kmers_combined_p_value = depleted_kmers_combined_p_value$p_value
),
motif_kmers_df = motif_kmers_df,
volcano_plot = volcano_plot,
perm_test_plot = perm_test$plot,
enriched_kmers_combined_p_value = enriched_kmers_combined_p_value,
depleted_kmers_combined_p_value = depleted_kmers_combined_p_value
)
)
})
df <-
as.data.frame(do.call(
"rbind",
lapply(foreground_result, function(x)
x$df)
), stringsAsFactors = FALSE)
df$motif_id <- as.character(df$motif_id)
df$motif_rbps <- as.character(df$motif_rbps)
df$geo_mean_enrichment <-
as.numeric(df$geo_mean_enrichment)
df$p_value_estimate <-
as.numeric(df$p_value_estimate)
df$cont_int_low <- as.numeric(df$cont_int_low)
df$cont_int_high <- as.numeric(df$cont_int_high)
df$enriched_kmers_combined_p_value <-
as.numeric(df$enriched_kmers_combined_p_value)
df$depleted_kmers_combined_p_value <-
as.numeric(df$depleted_kmers_combined_p_value)
df$adj_p_value_estimate <-
stats::p.adjust(df$p_value_estimate,
method = p_adjust_method)
df$adj_enriched_kmers_combined_p_value <-
stats::p.adjust(df$enriched_kmers_combined_p_value,
method = p_adjust_method)
df$adj_depleted_kmers_combined_p_value <-
stats::p.adjust(df$depleted_kmers_combined_p_value,
method = p_adjust_method)
motif_kmers_dfs <-
lapply(foreground_result, function(x)
x$motif_kmers_df)
volcano_plots <-
lapply(foreground_result, function(x)
x$volcano_plot)
perm_test_plots <-
lapply(foreground_result, function(x)
x$perm_test_plot)
enriched_kmers_combined_p_values <-
lapply(foreground_result, function(x)
x$enriched_kmers_combined_p_value)
depleted_kmers_combined_p_values <-
lapply(foreground_result, function(x)
x$depleted_kmers_combined_p_value)
return(
list(
df = df,
motif_kmers_dfs = motif_kmers_dfs,
volcano_plots = volcano_plots,
perm_test_plots = perm_test_plots,
enriched_kmers_combined_p_values = enriched_kmers_combined_p_values,
depleted_kmers_combined_p_values = depleted_kmers_combined_p_values
)
)
})
result <-
lapply(seq_len(length(foreground_sets)), function(i) {
enrichment_df <- enrichment_result$dfs[[i]]
enrichment_df$kmer <- enrichment_result$kmers
return(
list(
enrichment_df = enrichment_df,
motif_df = motif_result[[i]]$df,
motif_kmers_dfs = motif_result[[i]]$motif_kmers_dfs,
volcano_plots = motif_result[[i]]$volcano_plots,
perm_test_plots = motif_result[[i]]$perm_test_plots,
enriched_kmers_combined_p_values = motif_result[[i]]$enriched_kmers_combined_p_values,
depleted_kmers_combined_p_values = motif_result[[i]]$depleted_kmers_combined_p_values
)
)
})
return(result)
} else {
return(NULL)
}
}
#' @title \emph{k}-mer-based Spectrum Motif Analysis
#'
#' @description
#' SPMA helps to illuminate the relationship between RBP binding evidence
#' and the transcript
#' sorting criterion, e.g., fold change between treatment and control samples.
#'
#' @param sorted_transcript_sequences character vector of ranked sequences,
#' either DNA
#' (only containing upper case characters A, C, G, T) or RNA (A, C, G, U).
#' The sequences in \code{sorted_transcript_sequences} must be
#' ranked (i.e., sorted).
#' Commonly used sorting criteria are measures of differential expression, such
#' as fold change or signal-to-noise ratio (e.g., between treatment and control
#' samples in gene expression profiling experiments).
#'
#' @inheritParams run_kmer_tsma
#' @inheritParams subdivide_data
#' @inheritParams score_spectrum
#'
#' @return A list with the following components:
#' \tabular{rl}{
#' \code{foreground_scores} \tab the result of \code{\link{run_kmer_tsma}}
#' for the binned data\cr
#' \code{spectrum_info_df} \tab a data frame with the SPMA results\cr
#' \code{spectrum_plots} \tab a list of spectrum plots, as generated by
#' \code{\link{score_spectrum}}\cr
#' \code{classifier_scores} \tab a list of classifier scores, as returned by
#' \code{\link{classify_spectrum}}
#' }
#'
#' @details
#' In order to investigate how motif targets are distributed across a
#' spectrum of
#' transcripts (e.g., all transcripts of a platform, ordered by fold change),
#' Spectrum Motif Analysis visualizes the gradient of RBP binding evidence
#' across all transcripts.
#'
#' The \emph{k}-mer-based approach differs from the matrix-based approach by
#' how the sequences are
#' scored. Here, sequences are broken into \emph{k}-mers, i.e.,
#' oligonucleotide sequences of
#' \emph{k} bases.
#' And only statistically significantly enriched or depleted \emph{k}-mers
#' are then used to
#' calculate a score for each RNA-binding protein, which quantifies its
#' target overrepresentation.
#'
#' @examples
#' # example data set
#' background_df <- transite:::ge$background_df
#' # sort sequences by signal-to-noise ratio
#' background_df <- dplyr::arrange(background_df, value)
#' # character vector of named and ranked (by signal-to-noise ratio) sequences
#' background_seqs <- gsub("T", "U", background_df$seq)
#' names(background_seqs) <- paste0(background_df$refseq, "|",
#' background_df$seq_type)
#'
#' results <- run_kmer_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "signal-to-noise ratio",
#' motifs = get_motif_by_id("M178_0.6"),
#' n_bins = 20,
#' fg_permutations = 10)
#'
#' \dontrun{
#' results <- run_kmer_spma(background_seqs,
#' sorted_transcript_values = background_df$value,
#' transcript_values_label = "signal-to-noise ratio")}
#'
#' @family SPMA functions
#' @family \emph{k}-mer functions
#' @importFrom stats p.adjust
#' @importFrom dplyr select
#' @importFrom dplyr filter
#' @export
run_kmer_spma <- function(sorted_transcript_sequences,
sorted_transcript_values = NULL,
transcript_values_label = "transcript value",
motifs = NULL,
k = 6,
n_bins = 40,
midpoint = 0,
x_value_limits = NULL,
max_model_degree = 1,
max_cs_permutations = 10000000,
min_cs_permutations = 5000,
fg_permutations = 5000,
p_adjust_method = "BH",
p_combining_method = "fisher",
n_cores = 1) {
# avoid CRAN note
motif_id <-
motif_rbps <-
adj_r_squared <- degree <- residuals <- slope <- NULL
f_statistic <-
f_statistic_p_value <- f_statistic_adj_p_value <- NULL
consistency_score <-
consistency_score_p_value <-
consistency_score_adj_p_value <- NULL
consistency_score_n <- aggregate_classifier_score <- NULL
n_significant <-
n_very_significant <- n_extremely_significant <- NULL
foreground_sets <- subdivide_data(sorted_transcript_sequences, n_bins)
results <- run_kmer_tsma(
foreground_sets,
sorted_transcript_sequences,
motifs = motifs,
k = k,
fg_permutations = fg_permutations,
kmer_significance_threshold = 0.01,
produce_plot = FALSE,
p_adjust_method = p_adjust_method,
p_combining_method = p_combining_method,
n_cores = n_cores
)
if (length(results) > 0) {
dfs <- lapply(results, function(result) {
result$motif_df
})
enrichment_df <- do.call("rbind", dfs)
enrichment_df$adj_p_value_estimate <-
stats::p.adjust(enrichment_df$p_value_estimate,
method = p_adjust_method
)
if (is.null(motifs)) {
motifs <- get_motifs()
}
spectrum_info <- lapply(motifs, function(motif) {
motif_data_df <- dplyr::filter(enrichment_df,
motif_id == get_id(motif))
values <- motif_data_df$geo_mean_enrichment
values[values == 0] <-
0.01 # avoid -Inf after taking the log
score <-
score_spectrum(
log(values),
p_values = motif_data_df$adj_p_value_estimate,
sorted_transcript_values = sorted_transcript_values,
transcript_values_label = transcript_values_label,
midpoint = midpoint,
x_value_limits = x_value_limits,
max_model_degree = max_model_degree,
max_cs_permutations = max_cs_permutations,
min_cs_permutations = min_cs_permutations
)
n_significant <-
sum(motif_data_df$adj_p_value_estimate <= 0.05)
classifier_score <-
classify_spectrum(
get_adj_r_squared(score),
get_model_degree(score),
get_model_slope(score),
get_consistency_score_n(score),
n_significant,
n_bins
)
return(
list(
info = list(
motif_id = get_id(motif),
motif_rbps = paste(get_rbps(motif), collapse = ", "),
adj_r_squared = get_adj_r_squared(score),
degree = get_model_degree(score),
residuals = get_model_residuals(score),
slope = get_model_slope(score),
f_statistic = get_model_f_statistic(score),
f_statistic_p_value = get_model_f_statistic_p_value(score),
consistency_score = get_consistency_score(score),
consistency_score_p_value = get_consistency_score_p_value(score),
consistency_score_n = get_consistency_score_n(score),
n_significant = n_significant,
n_very_significant = sum(motif_data_df$adj_p_value <= 0.01),
n_extremely_significant = sum(motif_data_df$adj_p_value <= 0.001),
aggregate_classifier_score = sum(classifier_score)
),
spectrum_plot = score@plot,
classifier_score = classifier_score
)
)
})
spectrum_info_df <-
as.data.frame(do.call("rbind", lapply(spectrum_info, function(x)
x$info)),
stringsAsFactors = FALSE
)
spectrum_info_df$motif_id <-
as.character(spectrum_info_df$motif_id)
spectrum_info_df$motif_rbps <-
as.character(spectrum_info_df$motif_rbps)
spectrum_info_df$adj_r_squared <-
as.numeric(spectrum_info_df$adj_r_squared)
spectrum_info_df$degree <-
as.integer(spectrum_info_df$degree)
spectrum_info_df$residuals <-
as.numeric(spectrum_info_df$residuals)
spectrum_info_df$slope <-
as.numeric(spectrum_info_df$slope)
spectrum_info_df$f_statistic <-
as.numeric(spectrum_info_df$f_statistic)
spectrum_info_df$f_statistic_p_value <-
as.numeric(spectrum_info_df$f_statistic_p_value)
spectrum_info_df$consistency_score <-
as.numeric(spectrum_info_df$consistency_score)
spectrum_info_df$consistency_score_p_value <-
as.numeric(spectrum_info_df$consistency_score_p_value)
spectrum_info_df$consistency_score_n <-
as.integer(spectrum_info_df$consistency_score_n)
spectrum_info_df$n_significant <-
as.integer(spectrum_info_df$n_significant)
spectrum_info_df$n_very_significant <-
as.integer(spectrum_info_df$n_very_significant)
spectrum_info_df$n_extremely_significant <-
as.integer(spectrum_info_df$n_extremely_significant)
spectrum_info_df$aggregate_classifier_score <-
as.integer(spectrum_info_df$aggregate_classifier_score)
spectrum_info_df$f_statistic_adj_p_value <-
stats::p.adjust(spectrum_info_df$f_statistic_p_value,
method = p_adjust_method)
spectrum_info_df$consistency_score_adj_p_value <-
stats::p.adjust(spectrum_info_df$consistency_score_p_value,
method = p_adjust_method)
spectrum_info_df <-
dplyr::select(
spectrum_info_df,
motif_id,
motif_rbps,
adj_r_squared,
degree,
residuals,
slope,
f_statistic,
f_statistic_p_value,
f_statistic_adj_p_value,
consistency_score,
consistency_score_p_value,
consistency_score_adj_p_value,
consistency_score_n,
n_significant,
n_very_significant,
n_extremely_significant,
aggregate_classifier_score
)
spectrum_plots <-
lapply(spectrum_info, function(x)
x$spectrum_plot)
classifier_scores <-
lapply(spectrum_info, function(x)
x$classifier_score)
} else {
stop("empty foreground sets")
}
return(
list(
foreground_scores = results,
spectrum_info_df = spectrum_info_df,
spectrum_plots = spectrum_plots,
classifier_scores = classifier_scores
)
)
}
R Package Documentation
Browse R Packages
We want your feedback!
Note that we can't provide technical support on individual packages. You should contact the package authors for that.
Embedding an R snippet on your website
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.