Crate lt_fm_index
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LT FM-Index
lt-fm-index
is library for locate and count nucleotide and amino acid sequence string.
lt-fm-index
use lookup table (LT) in count table
Description
- Fm-index is a data structure for exact pattern matching.
LT
is precalculated count table containing all kmer occurrences.LT
allows you to find the first k-mer pattern at once.
Features
LtFmIndex
is generated fromText
LtFmIndex
have two functions forPattern
- count: Count the number of times the
Pattern
appears inText
. - locate: Locate the start index in which the
Pattern
appears inText
.
- count: Count the number of times the
- Supports four types of text.
NucleotideOnly
supports a text with only genetic nucleotide sequence (ACGT).NucleotideWithNoise
supports a text containing non-nucleotide sequence.AminoacidOnly
supports a text with only amino acid sequence.AminoacidWithNoise
supports a text containing non-amino acid sequence.
- The last character of each text type is treated as a wildcard.
- The last characters of each text type are T, _, Y and _.
- Wildcard is assigned to all non-supported characters.
- For example, in
NucleotideOnly
, pattern of ACGTXYZ can be matched with ACGTTTT. Because X, Y and Z are not in ACG (nucleotide except T). Andlt-fm-index
generated with text of ACGTXYZ indexes the text as ACGTTTT.
- BWT is stored with rank count tables in every 64 or 128 intervals.
Examples
1. Use LtFmIndex
to count and locate pattern.
use lt_fm_index::LtFmIndexBuilder;
// (1) Define builder for lt-fm-index
let builder = LtFmIndexBuilder::new()
.use_nucleotide_with_noise()
.set_lookup_table_kmer_size(4).unwrap()
.set_suffix_array_sampling_ratio(2).unwrap();
// (2) Generate lt-fm-index with text
let text = b"CTCCGTACACCTGTTTCGTATCGGANNNN".to_vec();
let lt_fm_index = builder.build(text); // text is consumed
// (3) Match with pattern
let pattern = b"TA".to_vec();
// - count
let count = lt_fm_index.count(&pattern);
assert_eq!(count, 2);
// - locate
let locations = lt_fm_index.locate(&pattern);
assert_eq!(locations, vec![5,18]);
2. Save and load LtFmIndex
use lt_fm_index::{LtFmIndex, LtFmIndexBuilder};
// (1) Generate lt-fm-index
let text = b"CTCCGTACACCTGTTTCGTATCGGA".to_vec();
let lt_fm_index_to_save = LtFmIndexBuilder::new().build(text);
// (2) Save lt-fm-index to buffer
let mut buffer = Vec::new();
lt_fm_index_to_save.save_to(&mut buffer).unwrap();
// (3) Load lt-fm-index from buffer
let lt_fm_index_loaded = LtFmIndex::load_from(&buffer[..]).unwrap();
assert_eq!(lt_fm_index_to_save, lt_fm_index_loaded);
Repository
https://github.com/baku4/lt-fm-index
Doc
Reference
- Ferragina, P., et al. (2004). An Alphabet-Friendly FM-Index, Springer Berlin Heidelberg: 150-160.
- Anderson, T. and T. J. Wheeler (2021). An optimized FM-index library for nucleotide and amino acid search, Cold Spring Harbor Laboratory.
- Wang, Y., X. Li, D. Zang, G. Tan and N. Sun (2018). Accelerating FM-index Search for Genomic Data Processing, ACM.
- Yuta Mori.
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