example: GenomicFiles MAP on GRangesList

import_map_reduce.R

library(GenomicFiles)
register(SerialParam())
# use 4 BigWigs from
# ftp://hgdownload.cse.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeCshlLongRnaSeq/
files <- list.files("~/data/bigwig/",full=TRUE)
ranges0 <- GRanges("chr1",IRanges(11:20 * 1e6, width=1e5))
f <- factor(rep(1:2, each=length(ranges0)/2))
ranges <- split(ranges0, f)
MAP <- function(range, file) {
  rle <- import(file, which = range, as = "Rle", format = "bw")[range]
  mean(rle)
}
REDUCE <- function(mapped) {
  Reduce(cbind, mapped)
}
(res <- reduceByRange(ranges, files, MAP, REDUCE))
(resOut <- do.call(rbind, res))
sessionInfo()

import_map_reduce.Rout

> register(SerialParam())
> # use 4 BigWigs from
> # ftp://hgdownload.cse.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeCshlLongRnaSeq/
> files <- list.files("~/data/bigwig/",full=TRUE)
> ranges0 <- GRanges("chr1",IRanges(11:20 * 1e6, width=1e5))
> f <- factor(rep(1:2, each=length(ranges0)/2))
> ranges <- split(ranges0, f)
> MAP <- function(range, file) {
+   rle <- import(file, which = range, as = "Rle", format = "bw")[range]
+   mean(rle)
+ }
> REDUCE <- function(mapped) {
+   Reduce(cbind, mapped)
+ }
> (res <- reduceByRange(ranges, files, MAP, REDUCE))
$`1`
        init
chr1 0.08394 0.08899  4.58022 3.49198
chr1 0.04923 0.04763 10.90287 8.61417
chr1 0.03631 0.04303  0.00780 0.00727
chr1 0.03408 0.04532  2.16463 1.69084
chr1 0.01378 0.00825  0.01869 0.00581

$`2`
        init
chr1 0.13007 0.07382  3.83418  3.69978
chr1 0.91577 0.59110 50.07868 71.86047
chr1 0.01693 0.04954  0.18872  0.17385
chr1 0.00671 0.00805  0.20328  0.17623
chr1 1.12673 0.94558  0.05567  0.04120

> (resOut <- do.call(rbind, res))
        init
chr1 0.08394 0.08899  4.58022  3.49198
chr1 0.04923 0.04763 10.90287  8.61417
chr1 0.03631 0.04303  0.00780  0.00727
chr1 0.03408 0.04532  2.16463  1.69084
chr1 0.01378 0.00825  0.01869  0.00581
chr1 0.13007 0.07382  3.83418  3.69978
chr1 0.91577 0.59110 50.07868 71.86047
chr1 0.01693 0.04954  0.18872  0.17385
chr1 0.00671 0.00805  0.20328  0.17623
chr1 1.12673 0.94558  0.05567  0.04120
> sessionInfo()
R Under development (unstable) (2014-09-25 r66681)
Platform: x86_64-apple-darwin12.5.0 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats4    parallel  stats     graphics  grDevices datasets  utils
[8] methods   base

other attached packages:
 [1] GenomicFiles_1.1.19   BiocParallel_0.99.22  futile.logger_1.3.7
 [4] rtracklayer_1.25.16   Rsamtools_1.17.34     Biostrings_2.33.14
 [7] XVector_0.5.8         GenomicRanges_1.17.42 GenomeInfoDb_1.1.23
[10] IRanges_1.99.28       S4Vectors_0.2.4       BiocGenerics_0.11.5
[13] RUnit_0.4.27          devtools_1.6          slidify_0.4.5
[16] knitr_1.6             BiocInstaller_1.15.5

loaded via a namespace (and not attached):
 [1] base64enc_0.1-2          BatchJobs_1.4            BBmisc_1.7
 [4] bitops_1.0-6             brew_1.0-6               checkmate_1.4
 [7] codetools_0.2-9          DBI_0.3.1                digest_0.6.4
[10] evaluate_0.5.5           fail_1.2                 foreach_1.4.2
[13] formatR_1.0              futile.options_1.0.0     GenomicAlignments_1.1.30
[16] iterators_1.0.7          lambda.r_1.1.6           markdown_0.7.4
[19] RCurl_1.95-4.3           RSQLite_0.11.4           sendmailR_1.2-1
[22] stringr_0.6.2            tools_3.2.0              whisker_0.3-2
[25] XML_3.98-1.1             yaml_2.1.13              zlibbioc_1.11.1
>