gatk-3.8/protected/java/test/org/broadinstitute/sting
Mark DePristo bf42be44fc Fast DeBruijnGraph creation using the kmer counter
-- The previous creation algorithm used the following algorithm:

for each kmer1 -> kmer2 in each read
  add kmers 1 and 2 to the graph
  add edge kmer1 -> kmer2 in the graph, if it's not present (does check)
  update edge count by 1 if kmer1 -> kmer2 already existed in the graph

-- This algorithm had O(reads * kmers / read * (getEdge cost + addEdge cost)).  This is actually pretty expensive because get and add edges is expensive in jgrapht.
-- The new approach uses the following algorithm:

for each kmer1 -> kmer2 in each read
  add kmers 1 and 2 to a kmer counter, that counts kmer1+kmer2 in a fast hashmap

for each kmer pair 1 and 2 in the hash counter
  add edge kmer1 -> kmer2 in the graph, if it's not present (does check) with multiplicity count from map
  update edge count by count from map if kmer1 -> kmer2 already existed in the graph

-- This algorithm ensures that we add very much fewer edges
-- Additionally, created a fast kmer class that lets us create kmers from larger byte[]s of bases without cutting up the byte[] itself.
-- Overall runtimes are greatly reduced using this algorith
2013-04-10 17:10:59 -04:00
..
gatk/walkers Fast DeBruijnGraph creation using the kmer counter 2013-04-10 17:10:59 -04:00
utils Bug fix in SWPairwiseAlignment. 2013-04-10 16:04:37 -04:00