Convert exon coverage to polygons

Convert exon coverage to polygons

exoncov2polygon(
  gr,
  covNames = NULL,
  sample_id = NULL,
  baseline = NULL,
  gapWidth = 250,
  doPlot = FALSE,
  coord_style = c("fortify", "base", "list", "all"),
  ref2c = NULL,
  compress_introns = TRUE,
  verbose = FALSE,
  ...
)

Arguments

gr	GRanges where colnames(values(gr)) is present in covNames, and contains data with class NumericList.
covNames	character vector contained in colnames(values(gr)).
baseline	numeric vector of length 0, 1 or length(gr). If baseline has names matching names(gr) they will be used for each gr entry; if baseline is not named, it is extended to length(gr). The baseline value is added to the coverage for each exon to offset the polygon as needed.
gapWidth	numeric value sent to make_ref2compressed().
coord_style	character value to define the output style: "base" returns a matrix with polygons separated by a row of NA values; "fortify" returns a data.frame intended for ggplot2, with columns "cov" and "gr" indicating the values in covNames and names(gr) used to separate each polygon.
ref2c	optional list containing output from make_ref2compressed(), used to compress the GRanges coordinates.
compress_introns	logical indicating whether to compress the coverage polygon coordinates to approximately the same number of pixels per inch as the exon polygons. This option greatly reduces the size of the polygon, since introns are already about 50 to 100 times wider than exons, and when ref2c is supplied, the introns are visibly compressed to a fixed width on the x-axis. The data has many more x-axis coordinates than the data visualization, this argument is intended to reduce the intron coordinates accordingly.
verbose	logical indicating whether to print verbose output.
...	additional arguments are ignored.

Details

This function is a workhorse function that converts a GRanges object containing column values with NumericList coverage data, into a full data.frame sufficient to define ggplot2 and other coverage polygon plots.

An interesting argument is baseline which allows each exon in the gr GRanges object to be offset from zero, in order to make certain features visually easier to distinguish.

This function also calls simplifyXY() which reduces the stored polygon detail for regions whose coordinates are compressed on the x-axis, taking roughly the max value for each point.

The default output is roughly similar to broom::tidy() in that it converts a custom R object into a tidy data.frame suitable for use by ggplot2 and other tidy workflows.

The function getGRcoverageFromBw() takes a set of bigWig files and returns a GRanges object whose columns contain NumericList data, which is the intended input for exoncov2polygon().

See also

test_cov_wide_gr() for examples

Other jam GRanges functions: addGRLgaps(), addGRgaps(), annotateGRLfromGRL(), annotateGRfromGR(), assignGRLexonNames(), closestExonToJunctions(), combineGRcoverage(), findOverlapsGRL(), flattenExonsBy(), getFirstStrandedFromGRL(), getGRLgaps(), getGRcoverageFromBw(), getGRgaps(), grl2df(), jam_isDisjoint(), make_ref2compressed(), sortGRL(), spliceGR2junctionDF(), stackJunctions()

Other jam RNA-seq functions: assignGRLexonNames(), closestExonToJunctions(), combineGRcoverage(), defineDetectedTx(), detectedTxInfo(), flattenExonsBy(), getGRcoverageFromBw(), groups2contrasts(), internal_junc_score(), makeTx2geneFromGtf(), make_ref2compressed(), prepareSashimi(), runDiffSplice(), sortSamples(), spliceGR2junctionDF()

Other splicejam core functions: gene2gg(), grl2df(), make_ref2compressed(), plotSashimi(), prepareSashimi()

Examples

# use some test data
suppressPackageStartupMessages(library(GenomicRanges));
suppressPackageStartupMessages(library(ggplot2));
#> Warning: package ‘ggplot2’ was built under R version 3.6.2

data(test_cov_gr);
# prepare polygon coordinates
exondf <- exoncov2polygon(test_cov_gr, covNames="sample_A");
# create a ggplot
gg3 <- ggplot(exondf,
      aes(x=x, y=y, group=gr, fill=gr, color=gr)) +
   ggforce::geom_shape(alpha=0.8) +
   colorjam::theme_jam() +
   colorjam::scale_fill_jam() +
   colorjam::scale_color_jam();
print(gg3);