R/plotHist.R

In strandCheckR: Calculate strandness information of a bam file

#' @title Plot the histogram of positive proportions 
#'
#' @description Plot the histogram of positive proportions of the input 
#' histogram data frame
#'
#' @param windows data frame containing the strand information of the sliding 
#' windows. Windows can be obtained using the function \code{getWinFromBamFile}.
#' @param save if TRUE, then the plot will be save into the file given by 
#' \code{file} parameter
#' @param file the file name to save to plot
#' @param split an integer vector that specifies how you want to partition the 
#' windows based on the coverage. By default \code{split} = c(10,100,1000), 
#' which means that your windows will be partitionned into 4 groups, those have 
#' coverage < 10, from 10 to 100, from 100 to 1000, and > 1000
#' @param breaks an integer giving the number of bins for the histogram
#' @param useCoverage if TRUE then plot the coverage strand information, 
#' otherwise plot the number of reads strand information. FALSE by default
#' @param group_by the column names of windows that will be used to group 
#' the data
#' @param normalize_by the column names of windows that will be used to 
#' normalize the read count or read coverage into proportion
#' @param heatmap if TRUE, then use heat map to plot the histogram, otherwise 
#' use barplot. FALSE by default.
#' @param ... used to pass parameters to facet_wrap
#' 
#' @return If \code{heatmap=FALSE}: a ggplot object
#' 
#' @seealso \code{\link{getWinFromBamFile}}, \code{\link{plotWin}}
#'
#' @examples
#' bamfilein = system.file('extdata','s1.sorted.bam',package = 'strandCheckR')
#' win  <- getWinFromBamFile(file = bamfilein,sequences='10')
#' plotHist(win)
#' 
#' @importFrom gridExtra grid.arrange
#' @importFrom ggplot2 ggplot
#' @importFrom ggplot2 aes_string
#' @importFrom ggplot2 geom_bar geom_tile
#' @importFrom ggplot2 labs
#' @importFrom ggplot2 theme_bw theme element_blank
#' @importFrom grid unit
#' @importFrom ggplot2 facet_wrap
#' @importFrom ggplot2 ggsave ggtitle scale_fill_gradient
#' @importFrom dplyr filter
#' @export
plotHist <- function(
    windows, save = FALSE, file = "hist.pdf", group_by = NULL, 
    normalize_by = NULL, split = c(10, 100, 1000), breaks = 100, 
    useCoverage = FALSE, heatmap = FALSE, ...
    ) 
{
    histWin <- summarizeHist(
        windows, split = split, breaks = breaks, useCoverage = useCoverage, 
        group_by = group_by, normalize_by = normalize_by
        )
    # The initial checks for appropriate input
    reqWinCols <- c("PosProp", "ReadCountProp")
    stopifnot(all(reqWinCols %in% colnames(histWin)))
    stopifnot(is.logical(save))
    allows_facet_wrap <- setdiff(colnames(histWin), c(reqWinCols, "Coverage"))
    group_by <- intersect(group_by, allows_facet_wrap)
    
    # Make the plot
    if (heatmap == FALSE) {
        g <- ggplot(
            histWin, aes_string(
                x = "PosProp", y = "ReadCountProp", fill = "Coverage"
                )
            ) + 
            geom_bar(stat = "identity") + 
            labs(
                x = "Proportion of Reads on '+' Strand", 
                y = "Proportion of Windows"
                ) + 
            theme_bw() + 
            theme(plot.margin = unit(c(0.02, 0.04, 0.03, 0.02), "npc"))
        if (length(group_by) > 0) {
            # Get any facet arguments from dotArgs that have been set manually
            dotArgs <- list(...)
            allowed <- names(formals(facet_wrap))
            keepArgs <- names(dotArgs) %in% setdiff(allowed, "facets")
            argList <- c(list(facets = group_by), dotArgs[keepArgs])
            myFacets <- do.call(facet_wrap, argList)
            g <- g + myFacets
        }
    } else {
        cov <- unique(histWin$Coverage)
        g <- list()
        if (!("File" %in% colnames(histWin))) {
            histWin$File <- "File"
        }
        group_by <- group_by[group_by != "File"]
        if (length(group_by) > 0) {
            # Get any facet arguments from dotArgs that have been set manually
            dotArgs <- list(...)
            allowed <- names(formals(facet_wrap))
            keepArgs <- names(dotArgs) %in% setdiff(allowed, "facets")
            argList <- c(list(facets = group_by), dotArgs[keepArgs])
            myFacets <- do.call(facet_wrap, argList)
        }
        for (i in seq_along(cov)) {
            l <- filter(histWin, Coverage == cov[i])
            g[[i]] <- ggplot(
                l, aes_string(x = "PosProp", y = "File", fill = "ReadCountProp")
                ) + 
                geom_tile() + theme_bw() + 
                theme(
                    panel.grid.major = element_blank(), 
                    panel.grid.minor = element_blank()
                    ) + 
                scale_fill_gradient(
                    low = "white", high = "red", na.value = "white"
                    )
            if (length(group_by) > 0) {
                g[[i]] <- g[[i]] + myFacets
            }
            if (length(cov) > 1) {
                g[[i]] <- g[[i]] + ggtitle(paste0("Coverage ", cov[i]))
            }
        }
        g <- grid.arrange(grobs = g, nrow = length(cov))
    }
    
    if (save == TRUE) {
        message("The plot will be saved to the file ", file)
        dotArgs <- list(...)
        allowed <- names(formals(ggsave))
        keepArgs <- names(dotArgs) %in% setdiff(allowed, c("filename", "plot"))
        argList <- c(list(filename = file, plot = g), dotArgs[keepArgs])
        do.call(ggsave, argList)
    }
    if (heatmap == FALSE) return(g)
}