DNAString-class: DNAString objects

In Bioconductor/Biostrings: Efficient manipulation of biological strings

DNAString objects

Description

A DNAString object allows efficient storage and manipulation of a long DNA sequence.

Details

The DNAString class is a direct XString subclass (with no additional slot). Therefore all functions and methods described in the XString man page also work with a DNAString object (inheritance).

Unlike the BString container that allows storage of any single string (based on a single-byte character set) the DNAString container can only store a string based on the DNA alphabet (see below). In addition, the letters stored in a DNAString object are encoded in a way that optimizes fast search algorithms.

The DNA alphabet

This alphabet contains all letters from the IUPAC Extended Genetic Alphabet (see ?IUPAC_CODE_MAP) plus "-" (the gap letter), "+" (the hard masking letter), and "." (the not a letter or not available letter). It is stored in the DNA_ALPHABET predefined constant (character vector).

The alphabet() function returns DNA_ALPHABET when applied to a DNAString object.

Constructor-like functions and generics

In the code snippet below, x can be a single string (character vector of length 1), a BString object or an RNAString object.

DNAString(x="", start=1, nchar=NA):

Tries to convert x into a DNAString object by reading nchar letters starting at position start in x.

Accessor methods

In the code snippet below, x is a DNAString object.

alphabet(x, baseOnly=FALSE):

If x is a DNAString object, then return the DNA alphabet (see above). See the corresponding man pages when x is a BString, RNAString or AAString object.

Display

The letters in a DNAString object are colored when displayed by the show() method. Set global option Biostrings.coloring to FALSE to turn off this coloring.

Author(s)

H. Pagès

See Also

• The DNAStringSet class to represent a collection of DNAString objects.

• The XString and RNAString classes.

• reverseComplement

• alphabetFrequency

• IUPAC_CODE_MAP

• letter

Examples

DNA_BASES
DNA_ALPHABET
dna <- DNAString("TTGAAAA-CTC-N")
dna  # 'options(Biostrings.coloring=FALSE)' to turn off coloring

length(dna)
alphabet(dna)                 # DNA_ALPHABET
alphabet(dna, baseOnly=TRUE)  # DNA_BASES

Bioconductor/Biostrings documentation built on April 23, 2024, 5:45 a.m.