@peter.ralph

Relative Lempel-Ziv Compression of Genomes for Large-Scale Storage and Retrieval

, , and . String Processing and Information Retrieval, page 201--206. Berlin, Heidelberg, Springer Berlin Heidelberg, (2010)

Abstract

Self-indexes -- data structures that simultaneously provide fast search of and access to compressed text -- are promising for genomic data but in their usual form are not able to exploit the high level of replication present in a collection of related genomes. Our `RLZ' approach is to store a self-index for a base sequence and then compress every other sequence as an LZ77 encoding relative to the base. For a collection of r sequences totaling N bases, with a total of s point mutations from a base sequence of length n, this representation requires just \$nH\_k(T) + s\backslashlog n + s\backslashlog \backslashfrac\N\\s\ + O(s)\$bits. At the cost of negligible extra space, access to ℓ consecutive symbols requires \$\backslashO(\backslashell + \backslashlog n)\$time. Our experiments show that, for example, RLZ can represent individual human genomes in around 0.1 bits per base while supporting rapid access and using relatively little memory.

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