What is does
Reduces the size of a results set by taking a pileup file and producing a condensed version showing consecutive sequences of bases meeting coverage criteria. The tool works on six and ten column pileup formats produced with samtools pileup command. You also can specify columns for the input file manually. The tool assumes that the pileup dataset was produced by samtools pileup command (although you can override this by setting column assignments manually).
Types of pileup datasets
The description of pileup format below is largely based on information that can be found on SAMTools documentation page. The 6- and 10-column variants are described below.
Six column pileup:
1 2 3 4 5 6 --------------------------------- chrM 412 A 2 ., II chrM 413 G 4 ..t, IIIH chrM 414 C 4 ...a III2 chrM 415 C 4 TTTt III7
where:
Column Definition
------ ----------------------------
1 Chromosome
2 Position (1-based)
3 Reference base at that position
4 Coverage (# reads aligning over that position)
5 Bases within reads where (see Galaxy wiki for more info)
6 Quality values (phred33 scale, see Galaxy wiki for more)
Ten column pileup
The ten-column pileup incorporates additional consensus information generated with -c option of samtools pileup command:
1 2 3 4 5 6 7 8 9 10 ------------------------------------------------ chrM 412 A A 75 0 25 2 ., II chrM 413 G G 72 0 25 4 ..t, IIIH chrM 414 C C 75 0 25 4 ...a III2 chrM 415 C T 75 75 25 4 TTTt III7
where:
Column Definition
------- ----------------------------
1 Chromosome
2 Position (1-based)
3 Reference base at that position
4 Consensus bases
5 Consensus quality
6 SNP quality
7 Maximum mapping quality
8 Coverage (# reads aligning over that position)
9 Bases within reads where (see Galaxy wiki for more info)
10 Quality values (phred33 scale, see Galaxy wiki for more)
The output format
The output file condenses the information in the pileup file so that consecutive bases are listed together as sequences. The starting and ending points of the sequence range are listed, with the starting value converted to a 0-based value.
Given the following input with minimum coverage set to 3:
1 2 3 4 5 6 --------------------------------- chr1 112 G 3 ..Ta III6 chr1 113 T 2 aT.. III5 chr1 114 A 5 ,,.. IIH2 chr1 115 C 4 ,., III chrM 412 A 2 ., II chrM 413 G 4 ..t, IIIH chrM 414 C 4 ...a III2 chrM 415 C 4 TTTt III7 chrM 490 T 3 a I
the following would be the output:
1 2 3 4 ------------------- chr1 111 112 G chr1 113 115 AC chrM 412 415 GCC chrM 489 490 T
where:
Column Definition
------- ----------------------------
1 Chromosome
2 Starting position (0-based)
3 Ending position (1-based)
4 Sequence of bases