enrich_motifs {universalmotif} | R Documentation

## Enrich for input motifs in a set of sequences.

### Description

Given a set of target and background sequences, test if the input motifs are significantly enriched in the targets sequences relative to the background sequences. See the "Sequence manipulation and scanning" vignette.

### Usage

    enrich_motifs(motifs, sequences, bkg.sequences, max.p = 1e-05,
      max.q = 1e-05, max.e = 0.001, qval.method = "fdr", threshold = 0.001,
      threshold.type = "pvalue", verbose = 0, RC = FALSE, use.freq = 1,
      shuffle.k = 2, shuffle.method = "euler", return.scan.results = FALSE,
      nthreads = 1, rng.seed = sample.int(10000, 1), motif_pvalue.k = 8,
      use.gaps = TRUE, allow.nonfinite = FALSE, warn.NA = TRUE)

### Arguments

`motifs` | See `convert_motifs()` for acceptable motif formats.
`sequences` | `XStringSet` Sequences to scan. Alphabet should match motif.
`bkg.sequences` | `XStringSet` Optional. If missing, `shuffle_sequences()` is used to create background sequences from the input sequences.
`max.p` | `numeric(1)` P-value threshold.
`max.q` | `numeric(1)` Adjusted P-value threshold. This is only useful if multiple motifs are being enriched for.
`max.e` | `numeric(1)`. The E-value is calculated by multiplying the adjusted P-value with the number of input motifs times two (McLeay and Bailey 2010).
`qval.method` | `character(1)` See `stats::p.adjust()`.
`threshold` | `numeric(1)` See details.
`threshold.type` | `character(1)` One of `c('logodds', 'logodds.abs', 'pvalue')`. See details.
`verbose` | `numeric(1)` 0 for no output, 4 for max verbosity.
`RC` | `logical(1)` If `TRUE`, check reverse complement of input sequences.
`use.freq` | `numeric(1)` The default, 1, uses the motif matrix (from the `motif['motif']` slot) to search for sequences. If a higher number is used, then the matching k-let matrix from the `motif['multifreq']` slot is used. See `add_multifreq()`.
`shuffle.k` | `numeric(1)` The k-let size to use when shuffling input sequences. Only used if no background sequences are input. See `shuffle_sequences()`.
`shuffle.method` | `character(1)` One of `c('euler', 'markov', 'linear')`. See `shuffle_sequences()`.
`return.scan.results` | `logical(1)` Return output from `scan_sequences()`. For large jobs, leaving this as `FALSE` can save a small amount time by preventing construction of the complete results `data.frame` from `scan_sequences()`.
`nthreads` | `numeric(1)` Run `scan_sequences()` in parallel with `nthreads` threads. `nthreads = 0` uses all available threads. Note that no speed up will occur for jobs with only a single motif and sequence.
`rng.seed` | `numeric(1)` Set random number generator seed. Since shuffling can occur simultaneously in multiple threads using C++, it cannot communicate with the regular `R` random number generator state and thus requires an independent seed. Each individual sequence in an `XStringSet` object will be given the following seed: `rng.seed * index`. See `shuffle_sequences()`.
`motif_pvalue.k` | `numeric(1)` Control `motif_pvalue()` approximation. See `motif_pvalue()`.
`use.gaps` | `logical(1)` Set this to `FALSE` to ignore motif gaps, if present.
`allow.nonfinite` | `logical(1)` If `FALSE`, then apply a pseudocount if non-finite values are found in the PWM. Note that if the motif has a pseudocount greater than zero and the motif is not currently of type PWM, then this parameter has no effect as the pseudocount will be applied automatically when the motif is converted to a PWM internally. This value is set to `FALSE` by default in order to stay consistent with pre-version 1.8.0 behaviour.
`warn.NA` | `logical(1)` Whether to warn about the presence of non-standard letters in the input sequence, such as those in masked sequences.

### Details

To find enriched motifs, `scan_sequences()` is run on both target and background sequences. `stats::fisher.test()` is run to test for enrichment.

See `scan_sequences()` for more info on scanning parameters.

### Value

`DataFrame` Enrichment results in a `DataFrame`. Function args and (optionally) scan results are stored in the `metadata` slot.

### Author(s)

Benjamin Jean-Marie Tremblay b2tremblay@uwaterloo.ca

### References

McLeay R, Bailey TL (2010). “Motif Enrichment Analysis: A unified framework and method evaluation.” BMC Bioinformatics, 11(165).

### See Also

`scan_sequences()`, `shuffle_sequences()`, `add_multifreq()`, `motif_pvalue()`

### Examples

    data(ArabidopsisPromoters)
    data(ArabidopsisMotif)
    if (R.Version()$arch != "i386") {
    enrich_motifs(ArabidopsisMotif, ArabidopsisPromoters, threshold = 0.01)
    }

[Package universalmotif version 1.8.5 Index]