http://bioconductor.org/packages/devel/bioc/vignettes/GenomicRanges/inst/doc/GenomicRangesIntroduction.pdf (loaded with GenomicRanges)
endoapply and mendoapply perform the endomorphic equivalents of lapply and mapply by returning objects of the same class as the inputs rather than a list.
The return function should return object of the same class.
gr1 <- GRanges(
seqnames = "chr2",
ranges = IRanges(103, 106),
strand = "+",
score = 5L, GC = 0.45)
gr2 <- GRanges(
seqnames = c("chr1", "chr1"),
ranges = IRanges(c(107, 113), width = 3),
strand = c("+", "-"),
score = 3:4, GC = c(0.3, 0.5))
grl <- GRangesList("txA" = gr1, "txB" = gr2)
lapply(grl, length)
# $txA
# [1] 1
# $txB
# [1] 2
endoapply(grl, length)
# Error in .updateCompressedList(X, lapply_CompressedList(X, FUN, ...)) :
# 'FUN' must return elements of class GRanges
endoapply(grl, rev)
# GRangesList object of length 2:
# $txA
# GRanges object with 1 range and 2 metadata columns:
# seqnames ranges strand | score GC
# <Rle> <IRanges> <Rle> | <integer> <numeric>
# [1] chr2 [103, 106] + | 5 0.45
#
# $txB
# GRanges object with 2 ranges and 2 metadata columns:
# seqnames ranges strand | score GC
# [1] chr1 [113, 115] - | 4 0.5
# [2] chr1 [107, 109] + | 3 0.3
#
# -------
# seqinfo: 2 sequences from an unspecified genome; no seqlengths