R/plotCoverage.R

In RamsinghLab/ATACseeker: Utilities for ATACseq QC, differential accessibility, and integration

#' utility fn from Patrick Abouyoun's 2010 seminar
#'
#' @param x         a galp
#' @param gr        a single GRanges range (i.e. seqname, start, end)
#' @param col       what color to plot it
#' @param xlab      x axis label for the plot 
#' @param ylab      y axis label for the plot 
#' @param main      main title for the plot
#' @param stranded  plot stranded? (FALSE) 
#' @param smoothen  smooth the counts? (FALSE) 
#' @param kf        kernel function for smoothing (normal)
#' @param ...       arguments to pass along to coverage() 
#' 
#' @examples visualizing a specific enhancer:
#'
#' SMOenh <- GRanges('chr6', IRanges(29744702, 29751934), '+')
#' seqinfo(SMOenh) <- seqinfo(Mus.musculus)[seqlevels(SMOenh)]
#'
#' plotCoverage(galp, SMOenh)
#' plotCoverage(galp, SMOenh, stranded=TRUE)
#' plotCoverage(get5primeCuts(galp), SMOenh, stranded=TRUE)
#' plotCoverage(get5primeCuts(galp, shrink=FALSE), SMOenh, stranded=TRUE)
#'
#' @import GenomicRanges
#'
#' @export 
plotCoverage <- function(x, gr, col="violet", xlab="base", ylab="reads", 
                         main="Coverage", stranded=F, smoothen=0, kf='normal',
                         ...) {

  if(length(gr) > 1) {
    stop("This function only plots coverage for a single range...")
  } else {
    chr = as(seqnames(gr), 'character')
    if(smoothen > 0) {
      if(kf == 'exp') {
        wexp <- dexp(seq(0, 5, length.out=ceiling(smoothen/2)))
        wts <- round(c(rev(wexp), wexp)[1:smoothen], 5)
        wts <- wts/sum(wts)
      } else {
        wnorm <- dnorm(seq(0, 3, length.out=ceiling(smoothen/2)))
        wts <- round(c(rev(wnorm), wnorm)[1:smoothen], 5)
        wts <- wts/sum(wts)
      }
    }
    if(stranded == TRUE) { 
      pluscvg <- coverage(subset(x, strand == "+"), ...)[[chr]]
      minuscvg <- coverage(subset(x, strand == "-"), ...)[[chr]]
      revWin <- window(minuscvg, start(gr), end(gr))
      if(smoothen > 0) {
        revDepth = -1 * runwtsum(revWin, smoothen, wt=wts, endrule="constant")
      } else { 
        revDepth <- -1 * as(revWin, 'vector')
      }
    } else { 
      pluscvg <- coverage(x, ...)[[chr]]
      revDepth <- 0
    }
    fwdWin <- window(pluscvg, start(gr), end(gr))
    if(smoothen > 0) {
      fwdDepth = runwtsum(fwdWin, smoothen, wt=wts, endrule="constant")
    } else { 
      fwdDepth <- as(fwdWin, 'vector')
    }
  }

  x <- start(gr):end(gr)
  xlim <- c(start(gr), end(gr))
  ylim <- c(min(revDepth), max(fwdDepth))

  plot(x=start(gr), y=0, xlim=xlim, ylim=ylim, 
       xlab=xlab, ylab=ylab, main=main, type="n")
  polygon(c(start(gr), x, end(gr)), 
          c(0, as(fwdDepth, 'vector'), 0), 
          col=col)
  if(stranded == TRUE) {
    polygon(c(start(gr), x, end(gr)), 
            c(0, as(revDepth, 'vector'), 0), 
            col=col)
  }
}