bio-0.5.2: A bioinformatics library

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Bio.Alignment.Bowtie

Contents

- Data type and basic accessors
- Sequence positions of alignments
- Parsing Bowtie output
- Other utilities

Description

This module provides a data type to represent an alignment produced by the Bowtie short-read alignment tool (see http://bowtie-bio.sourceforge.net/index.shtml).

The simple accessors recapitulate the details of the Bowtie alignment output. The position of the alignment is given by the "0-based offset into the reference sequence where leftmost character of the alignment occurs". Thus, for forward-strand alignments this is the 5' end of the query sequence while for reverse-complement alignments this is the 3' end of the query sequence. Similarly, the query sequence and query quality are shown in reference forward strand orientation, and thus may be reverse complemented.

Synopsis

- data Align = Align {
  - name :: !SeqName
  - strand :: !Strand
  - refname :: !SeqName
  - leftoffset :: !Offset
  - sequ :: !SeqData
  - qual :: !QualData
  - mismatches :: ![Mismatch]
  }
- data Mismatch = Mismatch {
  - mmoffset :: !Offset
  - refbase :: !Char
  - readbase :: !Char
  }
- length :: Align -> Offset
- nmismatch :: Align -> Int
- querySequ :: Align -> SeqData
- queryQual :: Align -> QualData
- refCLoc :: Align -> ContigLoc
- refCSeqLoc :: Align -> ContigSeqLoc
- refSeqLoc :: Align -> SeqLoc
- refSeqPos :: Align -> SeqPos
- mismatchSeqPos :: Align -> Mismatch -> SeqPos
- parse :: ByteString -> Either String Align
- sameRead :: Align -> Align -> Bool

# Data type and basic accessors

data Align

Constructors

Align |

Fields

name :: !SeqName

  Name of the query sequence

strand :: !Strand

  Strand of the alignment on the reference sequence

refname :: !SeqName

  Name of the reference sequence

leftoffset :: !Offset

  Zero-based offset of the left-most aligned position in the reference

sequ :: !SeqData

  Query sequence, in the reference forward strand orientation

qual :: !QualData

  Query quality, in the reference forward strand orientation

mismatches :: ![Mismatch]

  Mismatches

Instances

Eq Align |
Ord Align |
Read Align |
Show Align |

data Mismatch

Representation of a single mismatch in a bowtie alignment

Constructors

Mismatch |

Fields

mmoffset :: !Offset

  Offset of the mismatch site from the 5' end of the query

refbase :: !Char

  Reference nucleotide

readbase :: !Char

  Query nucleotide

Instances

Eq Mismatch |
Ord Mismatch |
Read Mismatch |
Show Mismatch |

length :: Align -> Offset

Returns the length of the query sequence

nmismatch :: Align -> Int

Returns the number of mismatches in the alignment

querySequ :: Align -> SeqData

Query sequence as given in the query file

queryQual :: Align -> QualData

Query quality as given in the query file

# Sequence positions of alignments

refCLoc :: Align -> ContigLoc

As `refCSeqLoc` but without the reference sequence name.

refCSeqLoc :: Align -> ContigSeqLoc

Returns the sequence location covered by the query in the alignment. This will be a sequence location on the reference sequence and may run on the forward or the reverse complement strand.

refSeqLoc :: Align -> SeqLoc

Returns the sequence location covered by the query, as `refCSeqLoc`, as a `SeqLoc` location.

refSeqPos :: Align -> SeqPos

Returns the sequence position of the start of the query sequence alignment. This will include the strand of the alignment and will not be the same as the position computed from `leftoffset` when the alignment is on the reverse complement strand.

mismatchSeqPos :: Align -> Mismatch -> SeqPos

Sequence position of a mismatch on the reference sequence.

# Parsing Bowtie output

parse :: ByteString -> Either String Align

Parses a line of Bowtie output to produce a `Align`

# Other utilities

sameRead :: Align -> Align -> Bool

Returns true when two alignments were derived from the same sequencing read. As Bowtie writes alignments of query sequences in their order in the query file, all alignments of a given read are grouped together and the lists of all alignments for each read can be gathered with

     groupBy sameRead