R: Converts amino-acid three-letter code into the one-letter one

a {seqinr} | R Documentation

## Converts amino-acid three-letter code into the one-letter one

### Description

This is a vectorized function to convert three-letters amino-acid code into the one-letter one, for instance "Ala" into "A".

### Usage

    a(aa)

### Arguments

`aa` | A vector of string. All strings are 3 chars long.

### Details

Allowed character values for `aa` are given by `aaa()`. All other values will generate a warning and return NA. Called without arguments, `a()` returns the list of all possible output values.

### Value

A vector of single characters.

### Author(s)

D. Charif, J.R. Lobry

### References

The IUPAC one-letter code for aminoacids is described at: http://www.chem.qmul.ac.uk/iupac/AminoAcid/
`citation("seqinr")`

### See Also

`aaa`, `translate`

### Examples

      #
      # Show all possible input values:
      #

      aaa()

      #
      # Convert them in one letter-code:
      #

      a(aaa())

      #
      # Check consistency of results:
      #

      stopifnot( aaa(a(aaa())) == aaa())

      #
      # Show what happens with non-allowed values:
      #

      a("SOS") # should be NA and a warning is generated

[Package seqinr version 3.4-5 Index]