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@PoisonAlien
Last active November 9, 2023 21:21
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reading bam files in C using htslib
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <htslib/sam.h>
int main(int argc, char *argv[]){
samFile *fp_in = hts_open(argv[1],"r"); //open bam file
bam_hdr_t *bamHdr = sam_hdr_read(fp_in); //read header
bam1_t *aln = bam_init1(); //initialize an alignment
char *chrom = argv[2];
int locus = atoi(argv[3]);
int comp ;
printf("%s\t%d\n", chrom, locus);
//header parse
//uint32_t *tar = bamHdr->text ;
//uint32_t *tarlen = bamHdr->target_len ;
//printf("%d\n",tar);
while(sam_read1(fp_in,bamHdr,aln) > 0){
int32_t pos = aln->core.pos +1; //left most position of alignment in zero based coordianate (+1)
char *chr = bamHdr->target_name[aln->core.tid] ; //contig name (chromosome)
uint32_t len = aln->core.l_qseq; //length of the read.
uint8_t *q = bam_get_seq(aln); //quality string
uint32_t q2 = aln->core.qual ; //mapping quality
char *qseq = (char *)malloc(len);
for(int i=0; i< len ; i++){
qseq[i] = seq_nt16_str[bam_seqi(q,i)]; //gets nucleotide id and converts them into IUPAC id.
}
//printf("%s\t%d\t%d\t%s\t%s\t%d\n",chr,pos,len,qseq,q,q2);
if(strcmp(chrom, chr) == 0){
if(locus > pos+len){
printf("%s\t%d\t%d\t%s\t%s\t%d\n",chr,pos,len,qseq,q,q2);
}
}
}
bam_destroy1(aln);
sam_close(fp_in);
return 0;
}
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