r738: output multi-map in the XA tag (SE only)

... PE support coming soon

bwamem.c

@@ -67,6 +67,7 @@ mem_opt_t *mem_opt_init()
 	o->split_factor = 1.5;
 	o->chunk_size = 10000000;
 	o->n_threads = 1;
+	o->max_hits = 10;
 	o->max_matesw = 100;
 	o->mask_level_redun = 0.95;
 	o->min_chain_weight = 0;
@@ -898,6 +899,7 @@ void mem_aln2sam(const bntseq_t *bns, kstring_t *str, bseq1_t *s, int n, const m
 			}
 		}
 	}
+	if (p->XA) { kputsn("\tXA:Z:", 6, str); kputs(p->XA, str); }
 	if (s->comment) { kputc('\t', str); kputs(s->comment, str); }
 	kputc('\n', str);
 }
@@ -934,10 +936,14 @@ int mem_approx_mapq_se(const mem_opt_t *opt, const mem_alnreg_t *a)
 // TODO (future plan): group hits into a uint64_t[] array. This will be cleaner and more flexible
 void mem_reg2sam_se(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, bseq1_t *s, mem_alnreg_v *a, int extra_flag, const mem_aln_t *m)
 {
+	extern char **mem_gen_alt(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, mem_alnreg_v *a, int l_query, const char *query);
 	kstring_t str;
 	kvec_t(mem_aln_t) aa;
 	int k;
+	char **XA = 0;
 
+	if (!(opt->flag & MEM_F_ALL))
+		XA = mem_gen_alt(opt, bns, pac, a, s->l_seq, s->seq);
 	kv_init(aa);
 	str.l = str.m = 0; str.s = 0;
 	for (k = 0; k < a->n; ++k) {
@@ -948,10 +954,8 @@ void mem_reg2sam_se(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pa
 		if (p->secondary >= 0 && p->score < a->a[p->secondary].score * opt->drop_ratio) continue;
 		q = kv_pushp(mem_aln_t, aa);
 		*q = mem_reg2aln2(opt, bns, pac, s->l_seq, s->seq, p, s->name);
-		if (q->rid < 0) {
-			--aa.n;
-			continue;
-		}
+		assert(q->rid >= 0); // this should not happen with the new code
+		q->XA = XA? XA[k] : 0;
 		q->flag |= extra_flag; // flag secondary
 		if (p->secondary >= 0) q->sub = -1; // don't output sub-optimal score
 		if (k && p->secondary < 0) // if supplementary
@@ -966,10 +970,14 @@ void mem_reg2sam_se(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pa
 	} else {
 		for (k = 0; k < aa.n; ++k)
 			mem_aln2sam(bns, &str, s, aa.n, aa.a, k, m, opt->flag&MEM_F_SOFTCLIP);
-		for (k = 0; k < aa.n; ++k) free(aa.a[k].cigar);
+		for (k = 0; k < aa.n; ++k) {
+			free(aa.a[k].cigar);
+			free(aa.a[k].XA);
+		}
 		free(aa.a);
 	}
 	s->sam = str.s;
+	if (XA) free(XA);
 }
 
 mem_alnreg_v mem_align1_core(const mem_opt_t *opt, const bwt_t *bwt, const bntseq_t *bns, const uint8_t *pac, int l_seq, char *seq)

bwamem.h

@@ -47,6 +47,7 @@ typedef struct {
 	int mapQ_coef_fac;
 	int max_ins;            // when estimating insert size distribution, skip pairs with insert longer than this value
 	int max_matesw;         // perform maximally max_matesw rounds of mate-SW for each end
+	int max_hits;           // if there are max_hits or fewer, output them all
 	int8_t mat[25];         // scoring matrix; mat[0] == 0 if unset
 } mem_opt_t;
 
@@ -82,6 +83,7 @@ typedef struct { // This struct is only used for the convenience of API.
 	uint32_t is_rev:1, mapq:8, NM:23; // is_rev: whether on the reverse strand; mapq: mapping quality; NM: edit distance
 	int n_cigar;     // number of CIGAR operations
 	uint32_t *cigar; // CIGAR in the BAM encoding: opLen<<4|op; op to integer mapping: MIDSH=>01234
+	char *XA;        // alternative mappings
 
 	int score, sub;
 } mem_aln_t;

bwamem_extra.c

@@ -100,9 +100,48 @@ void mem_reg2ovlp(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac,
 		kputw(bns->anns[rid].len, &str); kputc('\t', &str);
 		kputw(pos, &str); kputc('\t', &str); kputw(pos + (re - rb), &str); kputc('\t', &str);
 		ksprintf(&str, "%.3f", (double)p->truesc / opt->a / (qe - qb > re - rb? qe - qb : re - rb));
-		kputc('\t', &str); kputw(p->n_comp, &str);
 		kputc('\n', &str);
 	}
 	s->sam = str.s;
 }
 
+// Okay, returning strings is bad, but this has happened a lot elsewhere. If I have time, I need serious code cleanup.
+char **mem_gen_alt(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, const mem_alnreg_v *a, int l_query, const char *query) // ONLY work after mem_mark_primary_se()
+{
+	int i, k, *cnt, tot;
+	kstring_t *aln = 0;
+	char **XA = 0;
+
+	cnt = calloc(a->n, sizeof(int));
+	for (i = 0, tot = 0; i < a->n; ++i) {
+		int j = a->a[i].secondary;
+		if (j >= 0 && a->a[i].score >= a->a[j].score * opt->drop_ratio)
+			++cnt[j], ++tot;
+	}
+	if (tot == 0) goto end_gen_alt;
+	aln = calloc(a->n, sizeof(kstring_t));
+	for (i = 0; i < a->n; ++i) {
+		mem_aln_t t;
+		int j = a->a[i].secondary;
+		if (j < 0 || a->a[i].score < a->a[j].score * opt->drop_ratio) continue; // we don't process the primary alignments as they will be converted to SAM later
+		if (cnt[j] > opt->max_hits) continue;
+		t = mem_reg2aln(opt, bns, pac, l_query, query, &a->a[i]);
+		kputs(bns->anns[t.rid].name, &aln[j]);
+		kputc(',', &aln[j]); kputc("+-"[t.is_rev], &aln[j]); kputl(t.pos + 1, &aln[j]);
+		kputc(',', &aln[j]);
+		for (k = 0; k < t.n_cigar; ++k) {
+			kputw(t.cigar[k]>>4, &aln[j]);
+			kputc("MIDSHN"[t.cigar[k]&0xf], &aln[j]);
+		}
+		kputc(',', &aln[j]); kputw(t.NM, &aln[j]);
+		kputc(';', &aln[j]);
+		free(t.cigar);
+	}
+	XA = calloc(a->n, sizeof(char*));
+	for (k = 0; k < a->n; ++k)
+		XA[k] = aln[k].s;
+
+end_gen_alt:
+	free(cnt); free(aln);
+	return XA;
+}

bwamem_pair.c

@@ -313,7 +313,8 @@ int mem_sam_pe(const mem_opt_t *opt, const bntseq_t *bns, const uint8_t *pac, co
 		mem_aln2sam(bns, &str, &s[0], 1, &h[0], 0, &h[1], opt->flag&MEM_F_SOFTCLIP); s[0].sam = strdup(str.s); str.l = 0;
 		mem_aln2sam(bns, &str, &s[1], 1, &h[1], 0, &h[0], opt->flag&MEM_F_SOFTCLIP); s[1].sam = str.s;
 		if (strcmp(s[0].name, s[1].name) != 0) err_fatal(__func__, "paired reads have different names: \"%s\", \"%s\"\n", s[0].name, s[1].name);
-		free(h[0].cigar); free(h[1].cigar);
+		free(h[0].cigar); free(h[0].XA);
+		free(h[1].cigar); free(h[1].XA);
 	} else goto no_pairing;
 	return n;
 

main.c

@@ -4,7 +4,7 @@
 #include "utils.h"
 
 #ifndef PACKAGE_VERSION
-#define PACKAGE_VERSION "0.7.8-r737-dirty"
+#define PACKAGE_VERSION "0.7.8-r738-dirty"
 #endif
 
 int bwa_fa2pac(int argc, char *argv[]);