read.Mask {Biostrings} | R Documentation

## Read a mask from a file

### Description

Five functions – `read.agpMask`, `read.gapMask`, `read.liftMask`, `read.rmMask` and `read.trfMask` – for extracting a mask from an NCBI "agp" file, an UCSC "gap" file, an UCSC "lift" file (i.e. a file containing offsets of contigs within sequences), a RepeatMasker .out file, or a Tandem Repeats Finder .bed file.

### Usage

      read.agpMask(file, width, seqname="?", gap.types=NULL, use.gap.types=FALSE)
      read.gapMask(file, width, seqname="?", gap.types=NULL, use.gap.types=FALSE)
      read.liftMask(file, seqname="?", width=NA)
      read.rmMask(file, width, use.IDs=FALSE)
      read.trfMask(file, width)

### Arguments

`file` | Either a character string naming a file or a connection open for reading.
`width` | The width of the mask to return. See `?`MaskCollection-class`` for more information about the width of a MaskCollection object.
`seqname` | The name of the sequence for which the mask must be extracted. If no sequence is specified (i.e. `seqname="?"`) then an error is raised and the sequence names found in the file are displayed. If the file doesn't contain any information for the specified sequence, then a warning is issued and an empty mask of width `width` is returned.
`gap.types` | `NULL` or a character vector containing gap types. Use this argument to filter the assembly gaps that are to be extracted from the "agp" or "gap" file based on their type. Most common gap types are `"contig"`, `"clone"`, `"centromere"`, `"telomere"`, `"heterochromatin"`, `"short_arm"` and `"fragment"`. With `gap.types=NULL`, all the assembly gaps described in the file are extracted. With `gap.types="?"`, an error is raised and the gap types found in the file for the specified sequence are displayed.
`use.gap.types` | Whether or not the gap types provided in the "agp" or "gap" file should be used to name the ranges constituing the returned mask. See `?`IRanges-class`` for more information about the names of an IRanges object.
`use.IDs` | Whether or not the repeat IDs provided in the RepeatMasker .out file should be used to name the ranges constituing the returned mask. See `?`IRanges-class`` for more information about the names of an IRanges object.

### See Also

`maskMotif`, MaskCollection-class, MaskedXString-class, IRanges-class

### Examples

      ## ---------------------------------------------------------------------
      ## A. Extract a mask of "assembly gaps" with read.agpMask()
      ## ---------------------------------------------------------------------
      ## Note: The hs_b36v3_chrY.agp file was obtained by downloading,
      ## extracting and renaming the hs_ref_chrY.agp.gz file from
      ##
      ##   ftp://ftp.ncbi.nih.gov/genomes/H_sapiens/Assembled_chromosomes/
      ##     hs_ref_chrY.agp.gz      5 KB  24/03/08  04:33:00 PM
      ##
      ## on May 9, 2008.

      file1 <- system.file("extdata", "hs_b36v3_chrY.agp", package="Biostrings")
      mask1 <- read.agpMask(file1, 57772954, seqname="chrY", use.gap.types=TRUE)
      mask1
      mask1[[1]]

      mask11 <- read.agpMask(file1, 57772954, seqname="chrY",
                             gap.types=c("centromere", "heterochromatin"))
      mask11[[1]]

      ## ---------------------------------------------------------------------
      ## B. Extract a mask of "inter-contig gaps" with read.liftMask()
      ## ---------------------------------------------------------------------
      ## Note: The hg18liftAll.lft file was obtained by downloading,
      ## extracting and renaming the liftAll.zip file from
      ##
      ##   http://hgdownload.cse.ucsc.edu/goldenPath/hg18/bigZips/
      ##     liftAll.zip             03-Feb-2006 11:35  5.5K
      ##
      ## on May 8, 2008.

      file2 <- system.file("extdata", "hg18liftAll.lft", package="Biostrings")
      mask2 <- read.liftMask(file2, seqname="chr1")
      mask2
      if (interactive()) {
          ## contigs 7 and 8 for chrY are adjacent
          read.liftMask(file2, seqname="chrY")

          ## displays the sequence names found in the file
          read.liftMask(file2)

          ## specify an unknown sequence name
          read.liftMask(file2, seqname="chrZ", width=300)
      }

      ## ---------------------------------------------------------------------
      ## C. Extract an "rm" or a "trf" mask with read.rmMask() or
      ##    read.trfMask()
      ## ---------------------------------------------------------------------
      ## Note: The ce2chrM.fa.out and ce2chrM.bed files were obtained by
      ## downloading, extracting and renaming the chromOut.zip and
      ## chromTrf.zip files from
      ##
      ##   http://hgdownload.cse.ucsc.edu/goldenPath/ce2/bigZips/
      ##     chromOut.zip            21-Apr-2004 09:05  2.6M
      ##     chromTrf.zip            21-Apr-2004 09:07  182K
      ##
      ## on May 7, 2008.

      ## Before you can extract a mask with read.rmMask() or read.trfMask(), you
      ## need to know the length of the sequence that you're going to put the
      ## mask on:
      library(BSgenome.Celegans.UCSC.ce2)
      chrM <- Celegans$chrM
      mask_width <- length(chrM)

      ## Read the RepeatMasker .out file for chrM in ce2:
      file3 <- system.file("extdata", "ce2chrM.fa.out", package="Biostrings")
      mask3 <- read.rmMask(file3, mask_width)
      mask3
      names(mask3) <- "RepeatMasker"
      mask3

      ## Read the Tandem Repeats Finder .bed file for chrM in ce2:
      file4 <- system.file("extdata", "ce2chrM.bed", package="Biostrings")
      mask4 <- read.trfMask(file4, mask_width)
      mask4
      names(mask4) <- "Tandem Repeats Finder [period<=12]"
      mask4

      ## Put the 2 masks on chrM:
      masks(chrM) <- mask3  # this would drop all current masks, if any
      masks(chrM) <- append(masks(chrM), mask4)
      chrM

[Package Biostrings version 2.8.18 Index]