Yesterday, I wrote one code to load a vcf file with 20million lines into the memory. It's a huge hash, taking more than 5 G of memory. Today, I checked the perl module Vcf.pm. It's very fast and memory-efficency. Generally, I beleive their codes have been better tested than mine. I ...
https://www.biostars.org/p/65558/ Converting Genome Coordinates From One Genome Version To Another (Ucsc Liftover, Ncbi Remap, Ensembl Api) 很好的总结,that is.