[Bioperl-l] Extracting Raw Score Value from Blast Output
Waibhav Tembe
tembe at bioanalysis.org
Thu Dec 9 15:28:46 EST 2004
Hello,
I am relatively new to BLAST and BioPerl. Apologies if this
question/observation is trivial or I have made any basic mistake.
I am parsing BLAST output using *bioperl-1.4::Bio::Search::Hit* <toc.html>.
For a given hit, I would like to extract raw score, bit score and other
information. Using
->raw_score
->Bits
for a hit. Here is what I observed. (Just pasting relevant info from
BLAST output)
================================================
Query= PA008
(35 letters)
Database: All GenBank+EMBL+DDBJ+PDB sequences (but no EST, STS,
GSS,environmental samples or phase 0, 1 or 2 HTGS sequences)
2,718,617 sequences; 12,254,801,043 total letters
Searching..................................................done
Score E
Sequences producing significant alignments: (bits)
Value
gb|CP000001.1| Bacillus cereus ZK, complete genome
70 2e-10
omitted all other records ..........
>gb|CP000001.1| Bacillus cereus ZK, complete genome
Length = 5300915
Score = 69.9 bits (35), Expect = 2e-10
Identities = 35/35 (100%)
Strand = Plus / Plus
Query: 1 ttaacgaagcatcgcgaagagcacgttcaattgga 35
|||||||||||||||||||||||||||||||||||
Sbjct: 3032643 ttaacgaagcatcgcgaagagcacgttcaattgga 3032677
---------------------------------------------
For the above BLAST section, I generated the following statistics using
BioPerl.
Query Name = PA008
Lambda=1.37, Kappa=0.711, Base Match Reward=1
Checking Hit [1]Raw Score= 70 BitScore=69.9 EValue=2e-10
Bacillus cereus ZK, complete genome
I was expecting Raw Score = 35 and NOT 70. Is raw_score output by
BioPerl's implementation calculated differently? Am I reading BLAST
output incorreclty?
Thanks!
-waibhav
--
Waibhav Tembe.
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