A Fasta object contains biological sequences in the FASTA format. It is a small (S3)
extension to a data.frame. It is actually a data.frame containing at least two text columns
named Header and Sequence. The Header column contains the headerlines for each sequence,
and the Sequence columns the sequences themselves. A Fasta object is typically created by reading
a FASTA formatted file into R by readFasta.
A Fasta object can be treated as a data.frame, which makes it quick and easy to search both
Header and Sequence for specific regular expressions, sort or re-arrange the ordering of the sequences,
extract subsets or add new data to an existing Fasta object.
The plot.Fasta function will display the content of the Fasta object as a histogram over
the lengths of the sequences.
The summary.Fasta function will display a text giving the number of sequences and the alphabet,
i.e. listing all unique symbols found in the file.