PWMEnrich (version 4.8.2)

motifScores: Motif affinity of number of hits over a threshold

Description

Scan a number of sequences either to find overall affinity, or a number of hits over a score threshold.

Usage

motifScores(sequences, motifs, raw.scores = FALSE, verbose = TRUE, cutoff = NULL)

Arguments

sequences

a set of sequences to be scanned, a list of DNAString or other scannable objects

motifs

a list of motifs either as frequency matrices (PFM) or as PWM objects. If PFMs are specified they are converted to PWMs using uniform background.

raw.scores

if to return raw scores (odds) for each position in the sequence. Note that scores for forward and reverse strand are concatenated into a single long vector of scores (twice the length of the sequence)

verbose

if to print verbose output

cutoff

if not NULL, will count number of matches with score above value specified (instead of returning the average affinity). Can either be one value, or a vector of values for each of the motifs.

Value

if raw.scores=FALSE, returns a matrix of mean scores (after cutoff if any), where columns are motifs. The returned values are either mean odd scores (not log-odd), or number of hits above a threshold; otherwise if raw.scores=TRUE, returns a list of raw score values (before cutoff)

Examples

if(require("PWMEnrich.Dmelanogaster.background")){
   data(MotifDb.Dmel)

   affinity = motifScores(DNAString("CGTAGGATAAAGTAACTAGTTGATGATGAAAG"), MotifDb.Dmel) # affinity scores
   counts = motifScores(DNAString("CGTAGGATAAAGTAACTAGTTGATGATGAAAG"), MotifDb.Dmel, cutoff=log2(exp(4))) # motif hit count with Patser score of 4
   print(affinity)
   print(counts)

   # scanning multiple sequences
   sequences = list(DNAString("CGTAGGATAAAGTAACTAGTTGATGATGAAAG"), DNAString("TGAGACGAAGGGGATGAGATGCGGAAGAGTGAAA"))
   affinity2 = motifScores(sequences, MotifDb.Dmel)
   print(affinity2)
}