PeakSegJointHeuristicStep1 {PeakSegJoint}

PeakSegJointHeuristicStep1

Description

Run the first step of the PeakSegJoint fast heuristic optimization algorithm. This is the GridSearch subroutine of the JointZoom algorithm in arXiv:1506.01286. NB: this function is only for testing the C code against the R implementation (search tests/testthat/*.R for Step1). For real data see PeakSegJointSeveral.

Usage

PeakSegJointHeuristicStep1(profiles, 
    bin.factor = 2L)

Arguments

profiles

List of data.frames with columns chromStart, chromEnd, count, or single data.frame with additional column sample.id.

bin.factor

Size of bin pyramid. Bigger values result in slower computation.

Value

List of model fit results, which can be passed to ConvertModelList for easier interpretation.

Author(s)

Toby Dylan Hocking

Examples

library(PeakSegJoint)
library(ggplot2)
data(H3K36me3.TDH.other.chunk1, envir=environment())
lims <- c(43000000, 43200000) # left
some.counts <-
  subset(H3K36me3.TDH.other.chunk1$counts,
         lims[1] < chromEnd & chromStart < lims[2])
fit <- PeakSegJointHeuristicStep1(some.counts)
## Compute bins to show on plot as well.
profile.list <- split(some.counts, some.counts$sample.id)
bin.list <- list()
norm.list <- list()
for(sample.id in names(profile.list)){
  one <- profile.list[[sample.id]]
  max.count <- max(one$count)
  bins <- binSum(one, fit$bin_start_end[1], fit$bases_per_bin, fit$n_bins)
  stopifnot(fit$n_bins == nrow(bins))
  bins$mean <- with(bins, count/(chromEnd-chromStart))
  bins$mean.norm <- bins$mean/max.count
  stopifnot(bins$count >= 0)
  one$count.norm <- one$count/max.count
  norm.list[[sample.id]] <- one
  bin.list[[sample.id]] <- data.frame(sample.id, bins)
}
bin.df <- do.call(rbind, bin.list)
norm.df <- do.call(rbind, norm.list)
converted <- ConvertModelList(fit)
best.peaks <- transform(converted$peaks, y=peaks*-0.1, what="peaks")

if(require(ggplot2) && interactive()){

  ggplot()+
    scale_color_manual(values=c(data="grey50",
                                peaks="deepskyblue",
                                bins="black", segments="green"))+
    geom_step(aes(chromStart/1e3, count.norm, color=what),
              data=data.frame(norm.df, what="data"))+
    geom_segment(aes(chromStart/1e3, mean.norm,
                     xend=chromEnd/1e3, yend=mean.norm,
                     color=what),
                 data=data.frame(bin.df, what="bins"))+
    geom_segment(aes(chromStart/1e3, y,
                     xend=chromEnd/1e3, yend=y,
                     color=what),
                 size=1,
                 data=best.peaks)+
    geom_text(aes(chromStart/1e3, y,
                  label=paste0(peaks, " peak",
                               ifelse(peaks==1, "", "s"), " "),
                  color=what),
              hjust=1,
              size=3,
              vjust=0.5,
              data=best.peaks)+
    theme_bw()+
    theme(panel.margin=grid::unit(0, "cm"))+
    facet_grid(sample.id ~ ., scales="free")

}