Last data update: 2014.03.03

R: function performs TFBS prediction using the package rtfbs
rtfbsR Documentation

function performs TFBS prediction using the package rtfbs

Description

function performs TFBS prediction using the package rtfbs

Usage

## S4 method for signature 'cobindr'
rtfbs(x, append = F, background_scan = FALSE, n.cpu = NA)

Arguments

x

an object of the class "cobindr", which will hold all necessary information about the sequences and the hits.

append

logical flag, if append=TRUE the binding sites will be appended to already existing results

background_scan

logical flag, if background_scan=TRUE the background sequences will be searched for transcription factor binding sites

n.cpu

number of CPUs to be used for parallelization. Default value is 'NA' in which case the number of available CPUs is checked and than used.

Value

x

an object of the class "cobindr" including the predicted transcription factor binding sites

Author(s)

Yue-Hien Lee <>

References

uses the package "rtfbs" (http://cran.r-project.org/web/packages/rtfbs/index.html)

See Also

search.pwm, search.gadem

Examples


############################################################
# use simulated sequences
library(Biostrings)

n <- 400 # number of input sequences
l <- 500 # length of sequences
n.hits <- 250 # number of 'true' binding sites
bases <- c("A","C","G","T") # alphabet
# generate random input sequences with two groups with differing GC content
seqs <- sapply(1:(3*n/4), function(x) paste(sample(bases, l, replace=TRUE, 
		prob=c(.3,.22,.2,.28)), collapse=""))
seqs <- append(seqs, sapply(1:(n/4), function(x) paste(sample(bases, l, 
		replace=TRUE, prob=c(.25,.25,.25,.25)), collapse="")))
path <- system.file('extdata/pfms/myod.tfpfm',package='cobindR')
motif <- read.transfac.pfm(path)[[1]] # get PFM of binding site 
# add binding sites with distance specificity
for(position in c(110, 150)) {
	hits <- apply(apply(motif, 2, function(x) sample(x=bases, size=n.hits, 
			prob=x, replace=TRUE)), 1, paste, collapse='')
	pos.hits <- round(rnorm(n.hits, mean=position, sd=8))
	names(pos.hits) <- sample(1:n, n.hits)
	for(i in 1:n.hits) substr(seqs[as.integer(names(pos.hits)[i])], 
						start=pos.hits[i], stop=pos.hits[i]+ncol(motif)) <- hits[i] 
}
#save sample sequences in fasta file
tmp.file <- tempfile(pattern = "cobindr_sample_seq", tmpdir = tempdir(), fileext = ".fasta")
writeXStringSet(DNAStringSet(seqs), tmp.file)
#run cobindr
cfg <- cobindRConfiguration()
sequence_type(cfg) <- 'fasta'
sequence_source(cfg) <- tmp.file
sequence_origin(cfg) <- 'artificial sequences'
pfm_path(cfg) <- system.file('extdata/pfms',package='cobindR')
pairs(cfg) <- 'V$MYOD_01 V$MYOD_01'
fdrThreshold(cfg) <- 0 
runObj <- cobindr(cfg, name='cobindr test using sampled sequences')
# perform tfbs prediction using rtfbs
runObj.bs <- rtfbs(runObj)
# show results
plot.positionprofile(runObj.bs)

#clean up
unlink(tmp.file)

Results


R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(cobindR)

Attaching package: 'cobindR'

The following object is masked from 'package:base':

    sequence

> png(filename="/home/ddbj/snapshot/RGM3/R_BC/result/cobindR/rtfbs.Rd_%03d_medium.png", width=480, height=480)
> ### Name: rtfbs
> ### Title: function performs TFBS prediction using the package rtfbs
> ### Aliases: rtfbs rtfbs-method rtfbs,cobindr-method
> ### Keywords: manip iteration methods
> 
> ### ** Examples
> 
> 
> ############################################################
> # use simulated sequences
> library(Biostrings)
Loading required package: BiocGenerics
Loading required package: parallel

Attaching package: 'BiocGenerics'

The following objects are masked from 'package:parallel':

    clusterApply, clusterApplyLB, clusterCall, clusterEvalQ,
    clusterExport, clusterMap, parApply, parCapply, parLapply,
    parLapplyLB, parRapply, parSapply, parSapplyLB

The following objects are masked from 'package:stats':

    IQR, mad, xtabs

The following objects are masked from 'package:base':

    Filter, Find, Map, Position, Reduce, anyDuplicated, append,
    as.data.frame, cbind, colnames, do.call, duplicated, eval, evalq,
    get, grep, grepl, intersect, is.unsorted, lapply, lengths, mapply,
    match, mget, order, paste, pmax, pmax.int, pmin, pmin.int, rank,
    rbind, rownames, sapply, setdiff, sort, table, tapply, union,
    unique, unsplit

Loading required package: S4Vectors
Loading required package: stats4

Attaching package: 'S4Vectors'

The following objects are masked from 'package:base':

    colMeans, colSums, expand.grid, rowMeans, rowSums

Loading required package: IRanges
Loading required package: XVector
> 
> n <- 400 # number of input sequences
> l <- 500 # length of sequences
> n.hits <- 250 # number of 'true' binding sites
> bases <- c("A","C","G","T") # alphabet
> # generate random input sequences with two groups with differing GC content
> seqs <- sapply(1:(3*n/4), function(x) paste(sample(bases, l, replace=TRUE, 
+ 		prob=c(.3,.22,.2,.28)), collapse=""))
> seqs <- append(seqs, sapply(1:(n/4), function(x) paste(sample(bases, l, 
+ 		replace=TRUE, prob=c(.25,.25,.25,.25)), collapse="")))
> path <- system.file('extdata/pfms/myod.tfpfm',package='cobindR')
> motif <- read.transfac.pfm(path)[[1]] # get PFM of binding site 
[1] "ES_Sox2_1_c1058"
[1] "ES_Klf4_3_c1373"
> # add binding sites with distance specificity
> for(position in c(110, 150)) {
+ 	hits <- apply(apply(motif, 2, function(x) sample(x=bases, size=n.hits, 
+ 			prob=x, replace=TRUE)), 1, paste, collapse='')
+ 	pos.hits <- round(rnorm(n.hits, mean=position, sd=8))
+ 	names(pos.hits) <- sample(1:n, n.hits)
+ 	for(i in 1:n.hits) substr(seqs[as.integer(names(pos.hits)[i])], 
+ 						start=pos.hits[i], stop=pos.hits[i]+ncol(motif)) <- hits[i] 
+ }
> #save sample sequences in fasta file
> tmp.file <- tempfile(pattern = "cobindr_sample_seq", tmpdir = tempdir(), fileext = ".fasta")
> writeXStringSet(DNAStringSet(seqs), tmp.file)
> #run cobindr
> cfg <- cobindRConfiguration()
Warning message:
In .local(.Object, ...) :
  no config-file defined, generating configuration-object with default values
> sequence_type(cfg) <- 'fasta'
> sequence_source(cfg) <- tmp.file
> sequence_origin(cfg) <- 'artificial sequences'
> pfm_path(cfg) <- system.file('extdata/pfms',package='cobindR')
> pairs(cfg) <- 'V$MYOD_01 V$MYOD_01'
> fdrThreshold(cfg) <- 0 
> runObj <- cobindr(cfg, name='cobindr test using sampled sequences')
[1] "Creating a new experiment!"
reading file /tmp/Rtmpi0d0kP/cobindr_sample_seq698673fdbd86.fasta ...
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 reading pfm files: /home/ddbj/local/lib64/R/library/cobindR/extdata/pfms ...
[1] "ES_Sox2_1_c1058"
[1] "ES_Klf4_3_c1373"
[1] "ES_Oct4_1_c570"
[1] "ES_Sox2_1_c1058"
ignored files:
 
Using the parallel (multicore) version of cobindR - function cpg.gc.content with 4 cores
There were 50 or more warnings (use warnings() to see the first 50)
> # perform tfbs prediction using rtfbs
> runObj.bs <- rtfbs(runObj)
Loading required package: rtfbs
Starting binding site search with 4 PWMs.
Using the parallel (multicore) version of cobindR - function rtfbs.intern with 4 cores
Found 1449 binding sites.
Time difference of 4.122411 secs
> # show results
> plot.positionprofile(runObj.bs)
> 
> #clean up
> unlink(tmp.file)
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>