R/initialize_x.R

In gemini: GEMINI: Variational inference approach to infer genetic interactions from pairwise CRISPR screens

#' intialize_x
#' @description Initialize all x values to the value of \code{concordance}
#'
#' @param Model a Model object of class gemini.model
#' @param concordance a numeric value to initialize x
#' @param cores a numeric indicating the number of cores to use.  See \code{\link[gemini]{gemini_parallelization}} default 1.
#' @param verbose default FALSE
#'
#' @note As there is much hashing involved in this function, this tends to be computationally intensive.
#' As such, we have enabled parallelization of most hash steps, but this may still be rate-limited by the 
#' amount of memory consumed. 
#' 
#' @return a Model object of class gemini.model including new slots for x values and internal-use hashes
#'
#' @examples
#' data("Model", package = "gemini")
#' Model %<>% initialize_x()
#'
#' @importFrom magrittr set_names
#' @importFrom parallel mclapply
#' @export
initialize_x <- function(Model,
                         concordance = 1,
                         cores = 1,
                         verbose = FALSE) {
    # Check input
    stopifnot("gemini.model" %in% class(Model))
    
    # User message
    if (verbose)
        message("Initializing x")
    
    Input <- Model$Input
    LFC <- Input[[Model$LFC.name]]
    guide2gene <- Input[[Model$guide.pair.annot]]
    
    # single guide to paired genes hashmap
    hash = Sguide2Pguides_hash(guide2gene, Model$pattern_split, cores = cores)
    
    # paired guides corresponding to nc_gene;nc_gene
    remove_seq1 = guide2gene[(guide2gene[, 2] %in% Model$nc_gene), 1]
    remove_seq2 = guide2gene[(guide2gene[, 3] %in% Model$nc_gene), 1]
    
    # guides designed for nc_gene
    paired_guide_remove_seq1 = as.character(hash$paired_guide[remove_seq1, 1]) %>%
        unique()
    paired_guide_remove_seq2 = as.character(hash$paired_guide[remove_seq2, 2]) %>%
        unique()
    paired_guide_remove = c(paired_guide_remove_seq1, paired_guide_remove_seq2)
    
    # remove nc_gene guides from hashes
    hash$hash = hash$hash[!is.element(names(hash$hash), paired_guide_remove)]
    Model$hashes_x <- hash
    
    # single guide concordance
    if (length(concordance) == 1 & is.numeric(concordance)) {
        Model$x = x_seq = rep(concordance, length(names(hash$hash))) %>% magrittr::set_names(names(hash$hash))
        Model$x2 = x_seq ^ 2
    } else{
        stop(
            "No single concordance value specified. Please specify a single concordance value for x."
        )
    }
    
    # hash
    # genes corresponding to x_seq
    x_seq_genes = parallel::mclapply(
        X = names(x_seq),
        FUN = function(x) {
            gihj = hash$hash[[x]][1]
            ij = strsplit(gihj, split = Model$pattern_split, fixed = TRUE)[[1]]
            gene.col = which(ij == x) + 1
            g = guide2gene[match(gihj, guide2gene[, 1]), gene.col]
            return(g)
        },
        mc.cores = cores
    ) %>% unlist() %>% magrittr::set_names(names(x_seq))
    
    Model$hashes_x$gene_hash <- x_seq_genes

    # paired guides concordance
    xx_names = guide2gene[!(guide2gene[, 2] %in% Model$nc_gene |
                                guide2gene[, 3] %in% Model$nc_gene), 1]
    Model$xx = xx = rep(concordance, length(xx_names)) %>% magrittr::set_names(xx_names)
    Model$xx2 = xx ^ 2
    
    # output
    return(Model)
}