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flagstat
========
This example replicates the output of [samtools](https://samtools.github.io) flagstat command.
With a single core, the program is significantly slower, but the Go program comparable performance with 4 cores and surpassing the C implementation with 8.
On an example BAM file the output of samtools (1.3.2-199-gec1d68e/htslib 1.3.2-199-gec1d68e) is:
```
$ time samtools flagstat 9827_2#49.bam
56463236 + 0 in total (QC-passed reads + QC-failed reads)
0 + 0 secondary
0 + 0 supplementary
269248 + 0 duplicates
55357963 + 0 mapped (98.04% : N/A)
56463236 + 0 paired in sequencing
28231618 + 0 read1
28231618 + 0 read2
54363468 + 0 properly paired (96.28% : N/A)
55062652 + 0 with itself and mate mapped
295311 + 0 singletons (0.52% : N/A)
360264 + 0 with mate mapped to a different chr
300699 + 0 with mate mapped to a different chr (mapQ>=5)
real 1m31.517s
user 1m30.268s
sys 0m1.180s
```
and of this command (Go 1.8) on the same file is:
```
$ go build github.com/biogo/hts/paper/examples/flagstat
$ export GOMAXPROCS=1
$ time ./flagstat 9827_2#49.bam
56463236 + 0 in total (QC-passed reads + QC-failed reads)
0 + 0 in total secondary
0 + 0 in total supplementary
269248 + 0 duplicates
55357963 + 0 mapped (98.04% : N/A)
56463236 + 0 paired in sequencing
28231618 + 0 read1
28231618 + 0 read2
54363468 + 0 properly paired (96.28% : N/A)
55062652 + 0 with itself and mate mapped
295311 + 0 singletons (0.52% : N/A)
360264 + 0 with mate mapped to a different chr
300699 + 0 with mate mapped to a different chr (mapQ >= 5)
real 5m2.323s
user 5m0.312s
sys 0m2.148s
```
The following give the same flagstat output, but with reduced time.
GOMAXPROCS=2
```
real 2m41.310s
user 5m18.948s
sys 0m2.600s
```
GOMAXPROCS=4
```
real 1m40.957s
user 6m21.232s
sys 0m3.688s
```
GOMAXPROCS=8
```
real 1m28.465s
user 9m7.480s
sys 0m8.056s
```
The file used in the benchmark was 9827_2#49.bam, available from ftp://ftp.sra.ebi.ac.uk/vol1/ERA242/ERA242167/bam/9827_2%2349.bam
|
