refinePWMMotif {motifRG} | R Documentation

## create a PWM (Position Weight Model) model given a initial set of motif matches and input sequences

### Description

Create a PWM model given a initial set of motif matches and input sequences

### Usage

      refinePWMMotif(motifs=NULL, seqs,  pwm.ld= NULL, max.iter=50,
    tol=10^-4, mod="oops", null=rep(0.25, 4),pseudo=1, weights=rep(1,
    length(seqs)), motif.weights=NULL)

### Arguments

`motifs` | The initial set of motif matches. character vector or DNAStringSet object
`seqs` | Input sequences. character vector or DNAStringSet object
`pwm.ld` | The initial PWM matrixes in logodds transformation. Either "motifs" or "pwm.ld" is not NULL
`max.iter` | Maximum number of iterations for refinement
`tol` | Convergence criteria. The percentage of total PWM scores improvement required for convergence.
`mod` | Motif ocurrence model. If `mod=="oops"`, assume one motif match per sequence. If `mod=="zoops"`, assume zero or one motif match per sequence.
`null` | A numeric vector specifying the background model
`pseudo` | Pseudo counts for PWM construction
`weights` | a numeric vector specifying the weights for all sequences. Default: 1 for all sequences
`motif.weights` | a numeric vector specifying the weights for initial sets of motifs. Default: NULL

### Value

Return a list with two elements:

`model` | a list with two elements. "prob": PWM model, sum of columns add to 1. "logodd": PWM model in logodds form, log2 of original matrix substract the background model

.

`match` | a data.frame specifying the motif matches in each sequence. Columns are: "match": the sequence of the match, "score": PWM score, "strand", the strand of the match in the input sequence, "pos": start position of the motif match. If multiple matches are allowed, then "seq.id" specifies the index of the input sequence for the motif match.
`score` | Total PWM score of the motif matches

### See Also

`findMotif` `refinePWMMotifExtend`

### Examples

    ctcf.seq <- readDNAStringSet(system.file("extdata","ctcf.fa", package="motifRG"))
    data(ctcf.motifs)
    ### refine PWM model based on motif matches
    pwm.match <- refinePWMMotif(ctcf.motifs$motifs[[1]]@match$pattern, ctcf.seq)
    ### plot traditional motif logo
    library("seqLogo")
    seqLogo(pwm.match$model$prob)
    ### plot dinucleotide motif logo
    plotMotif(pwm.match$match$pattern)
    ### automatically extend PWM model
    pwm.match.extend <-refinePWMMotifExtend(ctcf.motifs$motifs[[1]]@match$pattern, ctcf.seq)
    ### plot the new motif matches
    plotMotif(pwm.match.extend$match$pattern)

[Package motifRG version 1.26.0 Index]