srf_index_hash(1) | Staden io_lib | srf_index_hash(1) |
srf_index_hash - Adds a hash-table index to an SRF file.
srf_index_hash [-c] srf_archive
srf_index_hash adds and index to an SRF file or replaces an existing index with a new one. In the case of concatenated SRF files only the index at the end of a file will be replaced, but internal indices will not be consulted by SRF tools.
The index is a hash table indexing the sequence names only. The name itself does not appear in the index, rather the top 7-bits of a 64-bit hash key are held in the index along with N-bits used to determine the hash bucket. This reduces the index size to around 10-15 bytes per sequence.
James Bonfield, Wellcome Trust Sanger Institute
September 29 |