7 #define MC_AVG_ERR 0.007
8 #define MC_MAX_SUMQ 3000
9 #define MC_MAX_SUMQP 1e-300
10 #define MC_MAX_EM_ITER 16
11 #define MC_EM_EPS 1e-4
16 double *q2p, *pdg; // pdg -> P(D|g)
18 double *z, *zswap; // aux for afs
19 double *CMk; // \binom{M}{k}
20 double *afs, *afs1; // afs: accumulative AFS; afs1: site posterior distribution
24 void mc_init_prior(mc_aux_t *ma, int type, double theta)
27 if (type == MC_PTYPE_COND2) {
28 for (i = 0; i <= 2 * ma->n; ++i)
29 ma->phi[i] = 2. * (i + 1) / (2 * ma->n + 1) / (2 * ma->n + 2);
30 } else if (type == MC_PTYPE_FLAT) {
31 for (i = 0; i <= ma->M; ++i)
32 ma->phi[i] = 1. / (ma->M + 1);
35 for (i = 0, sum = 0.; i < 2 * ma->n; ++i)
36 sum += (ma->phi[i] = theta / (2 * ma->n - i));
37 ma->phi[2 * ma->n] = 1. - sum;
41 mc_aux_t *mc_init(int n) // FIXME: assuming diploid
45 ma = calloc(1, sizeof(mc_aux_t));
46 ma->n = n; ma->M = 2 * n;
47 ma->q2p = calloc(MC_MAX_SUMQ + 1, sizeof(double));
48 ma->qsum = calloc(4 * ma->n, sizeof(int));
49 ma->bcnt = calloc(4 * ma->n, sizeof(int));
50 ma->pdg = calloc(3 * ma->n, sizeof(double));
51 ma->phi = calloc(2 * ma->n + 1, sizeof(double));
52 ma->z = calloc(2 * ma->n + 1, sizeof(double));
53 ma->zswap = calloc(2 * ma->n + 1, sizeof(double));
54 ma->afs = calloc(2 * ma->n + 1, sizeof(double));
55 ma->afs1 = calloc(2 * ma->n + 1, sizeof(double));
56 ma->CMk = calloc(ma->M + 1, sizeof(double));
57 for (i = 0; i <= MC_MAX_SUMQ; ++i)
58 ma->q2p[i] = pow(10., -i / 10.);
59 for (i = 0; i <= ma->M; ++i)
60 ma->CMk[i] = exp(lgamma(ma->M+1) - lgamma(ma->M-i+1) - lgamma(i+1));
61 mc_init_prior(ma, MC_PTYPE_FULL, 1e-3); // the simplest prior
65 void mc_destroy(mc_aux_t *ma)
68 free(ma->qsum); free(ma->bcnt);
69 free(ma->q2p); free(ma->pdg);
71 free(ma->z); free(ma->zswap);
72 free(ma->afs); free(ma->afs1);
78 static int sum_err(int *n, const bam_pileup1_t **plp, mc_aux_t *ma)
81 memset(ma->qsum, 0, sizeof(int) * 4 * ma->n);
82 memset(ma->bcnt, 0, sizeof(int) * 4 * ma->n);
83 for (j = 0; j < ma->n; ++j) {
84 int *qsum = ma->qsum + j * 4;
85 int *bcnt = ma->bcnt + j * 4;
86 for (i = 0; i < n[j]; ++i) {
87 const bam_pileup1_t *p = plp[j] + i;
89 if (p->is_del || (p->b->core.flag&BAM_FUNMAP)) continue;
90 q = bam1_qual(p->b)[p->qpos];
91 if (p->b->core.qual < q) q = p->b->core.qual;
92 if (q < MC_MIN_QUAL) continue; // small qual
93 b = bam_nt16_nt4_table[(int)bam1_seqi(bam1_seq(p->b), p->qpos)];
94 if (b > 3) continue; // N
103 static void set_allele(int ref, mc_aux_t *ma)
105 int i, j, sum[4], tmp;
106 sum[0] = sum[1] = sum[2] = sum[3] = 0;
107 for (i = 0; i < ma->n; ++i)
108 for (j = 0; j < 4; ++j)
109 sum[j] += ma->qsum[i * 4 + j];
110 for (j = 0; j < 4; ++j) sum[j] = sum[j]<<2 | j;
111 for (i = 1; i < 4; ++i) // insertion sort
112 for (j = i; j > 0 && sum[j] < sum[j-1]; --j)
113 tmp = sum[j], sum[j] = sum[j-1], sum[j-1] = tmp;
114 ma->ref = sum[3]&3; ma->alt = sum[2]&3; ma->alt2 = -1;
115 if (ma->ref != ref) { // the best base is not ref
116 if (ref >= 0 && ref <= 3) { // ref is not N
117 if (ma->alt == ref) tmp = ma->ref, ma->ref = ma->alt, ma->alt = tmp; // then switch alt and ref
118 else ma->alt2 = ma->alt, ma->alt = ma->ref, ma->ref = ref; // then set ref as ref
119 } else ma->alt2 = ma->alt, ma->alt = ma->ref, ma->ref = sum[0]&3; // then set the weakest as ref
123 static void cal_pdg(mc_aux_t *ma)
126 for (j = 0; j < ma->n; ++j) {
127 int pi[3], *qsum, *bcnt;
128 double *pdg = ma->pdg + j * 3;
129 qsum = ma->qsum + j * 4;
130 bcnt = ma->bcnt + j * 4;
131 pi[1] = 3 * (bcnt[ma->ref] + bcnt[ma->alt]);
132 pi[0] = qsum[ma->ref];
133 pi[2] = qsum[ma->alt];
134 for (i = 0; i < 3; ++i)
135 pdg[i] = pi[i] > MC_MAX_SUMQ? MC_MAX_SUMQP : ma->q2p[pi[i]];
138 // this calculates the naive allele frequency and Nielsen's frequency
139 static double mc_freq0(const mc_aux_t *ma, double *_f)
142 double f, f_nielsen, w_sum;
144 for (i = cnt = 0, f = f_nielsen = w_sum = 0.; i < ma->n; ++i) {
145 int *bcnt = ma->bcnt + i * 4;
146 int x = bcnt[ma->ref] + bcnt[ma->alt];
150 f += (double)bcnt[ma->ref] / x;
151 p = (bcnt[ma->ref] - MC_AVG_ERR * x) / (1. - 2. * MC_AVG_ERR) / x;
152 w = 2. * x / (1. + x);
159 if (f_nielsen < 0.) f_nielsen = 0.;
160 if (f_nielsen > 1.) f_nielsen = 1.;
165 // f0 is the reference allele frequency
166 static double mc_freq_iter(double f0, const mc_aux_t *ma)
170 f3[0] = (1.-f0)*(1.-f0); f3[1] = 2.*f0*(1.-f0); f3[2] = f0*f0;
171 for (i = 0, f = 0.; i < ma->n; ++i) {
173 pdg = ma->pdg + i * 3;
174 f += (pdg[1] * f3[1] + 2. * pdg[2] * f3[2])
175 / (pdg[0] * f3[0] + pdg[1] * f3[1] + pdg[2] * f3[2]);
181 int mc_call_gt(const mc_aux_t *ma, double f0, int k)
184 double max, f3[3], *pdg = ma->pdg + k * 3;
186 f3[0] = (1.-f0)*(1.-f0); f3[1] = 2.*f0*(1.-f0); f3[2] = f0*f0;
187 for (i = 0, sum = 0.; i < 3; ++i)
188 sum += (g[i] = pdg[i] * f3[i]);
189 for (i = 0, max = -1., max_i = 0; i < 3; ++i) {
191 if (g[i] > max) max = g[i], max_i = i;
194 if (max < 1e-308) max = 1e-308;
195 q = (int)(-3.434 * log(max) + .499);
200 static void mc_cal_z(mc_aux_t *ma)
202 double *z[2], *tmp, *pdg;
207 z[0][0] = 1.; z[0][1] = z[0][2] = 0.;
208 for (j = 0; j < ma->n; ++j) {
209 int max = (j + 1) * 2;
211 pdg = ma->pdg + j * 3;
212 p[0] = pdg[0]; p[1] = 2. * pdg[1]; p[2] = pdg[2];
213 z[1][0] = p[0] * z[0][0];
214 z[1][1] = p[0] * z[0][1] + p[1] * z[0][0];
215 for (i = 2; i <= max; ++i)
216 z[1][i] = p[0] * z[0][i] + p[1] * z[0][i-1] + p[2] * z[0][i-2];
217 if (j < ma->n - 1) z[1][max+1] = z[1][max+2] = 0.;
218 tmp = z[0]; z[0] = z[1]; z[1] = tmp;
220 if (z[0] != ma->z) memcpy(ma->z, z[0], sizeof(double) * (2 * ma->n + 1));
223 static double mc_add_afs(mc_aux_t *ma)
226 double sum = 0., avg = 0.;
227 memset(ma->afs1, 0, sizeof(double) * (ma->M + 1));
229 for (k = 0; k <= ma->M; ++k) {
230 for (l = 0, sum = 0.; l <= ma->M; ++l)
231 sum += ma->phi[l] * ma->z[l];
232 ma->afs1[k] = ma->phi[k] * ma->z[k] / sum;
234 for (k = 0; k <= ma->M; ++k)
235 if (isnan(ma->afs1[k]) || isinf(ma->afs1[k])) return -1.;
236 for (k = 0, sum = avg = 0.; k <= ma->M; ++k) {
237 ma->afs[k] += ma->afs1[k];
239 avg += k * ma->afs1[k];
241 // for (k = 0; k <= ma->M; ++k) printf("^%lg:%lg:%lg ", ma->z[k], ma->phi[k], ma->afs1[k]);
245 int mc_cal(int ref, int *n, const bam_pileup1_t **plp, mc_aux_t *ma, mc_rst_t *rst, int level)
248 memset(rst, 0, sizeof(mc_rst_t));
249 rst->f_em = rst->f_exp = -1.; rst->ref = rst->alt = -1;
251 tot = sum_err(n, plp, ma);
252 if (tot == 0) return 0; // no good bases
255 // set ref/major allele
256 rst->ref = ma->ref; rst->alt = ma->alt; rst->alt2 = ma->alt2;
257 // calculate naive and Nielsen's freq
258 rst->f_naive = mc_freq0(ma, &rst->f_nielsen);
260 double flast = rst->f_naive;
261 for (i = 0; i < MC_MAX_EM_ITER; ++i) {
262 rst->f_em = mc_freq_iter(flast, ma);
263 if (fabs(rst->f_em - flast) < MC_EM_EPS) break;
268 rst->f_exp = mc_add_afs(ma);
269 rst->p_ref = ma->afs1[ma->M];
274 void mc_dump_afs(mc_aux_t *ma)
277 fprintf(stderr, "[afs]");
278 for (k = 0; k <= ma->M; ++k)
279 fprintf(stderr, " %d:%.3lf", k, ma->afs[ma->M - k]);
280 fprintf(stderr, "\n");
281 memset(ma->afs, 0, sizeof(double) * (ma->M + 1));