The SequenceDB class: using sequence databases

The SequenceDB class holds a database of sequences. Such a database is similar to a multiple sequence alignment, but contains less auxiliary information (for example, no sequence may contain gaps). This requires less memory than a true alignment, and is thus more suited for large databases of sequences. Such a database can be scanned for matches to an input sequence with, used to build sequence profiles with or filtered by given criteria with SequenceDB.filter().