TEQC (version 3.12.0)

duplicates.barplot: Read duplicates barplot

Description

Barplot showing fractions of reads / read pairs which are unique and for which there are two, three, ... copies. Separate bars are made for on- and off-target reads / read pairs

Usage

duplicates.barplot(reads, targets, returnDups=FALSE, truncateX, col=c("red","lightblue"), xlab, ylab, ylim, ...)

Arguments

reads

RangedData table containing positions of sequenced reads, i.e. output from get.reads. Alternatively, for paired-end data, it can be the output of reads2pairs when multiplicities of read pairs instead of fraction of single reads shall be visualized.

targets

RangedData table containing positions of target regions, i.e. output from get.targets

returnDups

if TRUE, on- and off-target read / read pair multiplicities are returned

truncateX

integer; show bars only up to a read / read pair multiplicity of truncateX (x-axis)

col

vector specifying the two colors of bars and legend for on- and off-target read multiplicities

xlab, ylab

x- and y-axis labels

ylim

y-axis coordinate ranges

...

further graphical parameters passed to barplot

Value

with the respective number of copies (x-axis). Fractions are calculated separately for on- and off-target reads / read pairs. A read pair is considered on-target if at least one of its reads overlaps with a target. Absolute numbers (in millions) are additionally written on top of the bars.If returnDups equals TRUE, a list with two elements absolute and relative is returned. The former is a matrix that contains the absolute numbers of reads / read pairs for each multiplicity (columns), for both on- and off-target reads / read pairs (rows). The latter gives row-based fractions which correspond to the bar heights.

Details

Single-end reads are considered as duplicates if they have same start end end position. Paired-end read pairs are considered as duplicates if start and end positions of both reads of the pairs are identical. Usually, duplicates are removed before further analyses (e.g. SNP detection), because they could represent PCR artefacts. However, in target capture experiments it is likely to have also many "real" duplicates (actual different molecules that happen to start at same position) due to the "enrichment" of the target regions. The separation in the barplot between on- and off-target reads / read pairs gives an impression on whether on-target there are more reads with higher multiplicites, which hence might indicate a reasonable amount of "real" duplication. A paired-end read pair is considered on-target if at least one of its reads overlaps with a target.

See Also

get.reads, reads2pairs, get.targets

Examples

## get reads and targets
exptPath <- system.file("extdata", package="TEQC")
readsfile <- file.path(exptPath, "ExampleSet_Reads.bed")
reads <- get.reads(readsfile, idcol=4, skip=0)
targetsfile <- file.path(exptPath, "ExampleSet_Targets.bed")
targets <- get.targets(targetsfile, skip=0)

## duplicates barplot for single reads
duplicates.barplot(reads, targets, returnDups=TRUE)

## duplicates barplot for read pairs
readpairs <- reads2pairs(reads)
duplicates.barplot(readpairs, targets, returnDups=TRUE)