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)
17 double *phi, *alpha, *CMk; // CMk=\binom{M}{k}
18 double *z, *zswap; // aux for afs
19 double *afs, *afs1; // afs: accumulative AFS; afs1: site posterior distribution
23 static void precal_alpha(mc_aux_t *ma) // \alpha[k]=\binom{M}{k}\sum_l\phi_l(l/M)^k(1-l/M)^{M-k}
26 memset(ma->alpha, 0, sizeof(double) * (ma->M + 1));
27 for (l = 0; l <= ma->M; ++l)
28 ma->alpha[0] += ma->phi[l] * pow(1. - (double)l / ma->M, ma->M);
29 for (k = 1; k < ma->M; ++k) {
30 for (l = 1; l < ma->M; ++l) { // for k!=0 and k!=ma->M, l=0 and l=ma->M leads to zero
31 double x = exp((lgamma(ma->M + 1) - lgamma(k + 1) - lgamma(ma->M - k + 1))
32 + k * log((double)l / ma->M)
33 + (ma->M - k) * log(1. - (double)l / ma->M));
34 ma->alpha[k] += x * ma->phi[l];
37 for (l = 0; l <= ma->M; ++l)
38 ma->alpha[ma->M] += ma->phi[l] * pow((double)l / ma->M, ma->M);
42 void mc_init_prior(mc_aux_t *ma, int type, double theta)
45 if (type == MC_PTYPE_COND2) {
46 for (i = 0; i <= 2 * ma->n; ++i)
47 ma->phi[i] = 2. * (i + 1) / (2 * ma->n + 1) / (2 * ma->n + 2);
48 } else if (type == MC_PTYPE_FLAT) {
49 for (i = 0; i <= ma->M; ++i)
50 ma->phi[i] = 1. / (ma->M + 1);
53 for (i = 0, sum = 0.; i < 2 * ma->n; ++i)
54 sum += (ma->phi[i] = theta / (2 * ma->n - i));
55 ma->phi[2 * ma->n] = 1. - sum;
60 mc_aux_t *mc_init(int n) // FIXME: assuming diploid
64 ma = calloc(1, sizeof(mc_aux_t));
65 ma->n = n; ma->M = 2 * n;
66 ma->q2p = calloc(MC_MAX_SUMQ + 1, sizeof(double));
67 ma->qsum = calloc(4 * ma->n, sizeof(int));
68 ma->bcnt = calloc(4 * ma->n, sizeof(int));
69 ma->pdg = calloc(3 * ma->n, sizeof(double));
70 ma->phi = calloc(ma->M + 1, sizeof(double));
71 ma->alpha = calloc(ma->M + 1, sizeof(double));
72 ma->CMk = calloc(ma->M + 1, sizeof(double));
73 ma->z = calloc(2 * ma->n + 1, sizeof(double));
74 ma->zswap = calloc(2 * ma->n + 1, sizeof(double));
75 ma->afs = calloc(2 * ma->n + 1, sizeof(double));
76 ma->afs1 = calloc(2 * ma->n + 1, sizeof(double));
77 for (i = 0; i <= MC_MAX_SUMQ; ++i)
78 ma->q2p[i] = pow(10., -i / 10.);
79 for (i = 0; i <= ma->M; ++i)
80 ma->CMk[i] = exp(lgamma(ma->M + 1) - lgamma(i + 1) - lgamma(ma->M - i + 1));
81 mc_init_prior(ma, MC_PTYPE_FULL, 1e-3); // the simplest prior
85 void mc_destroy(mc_aux_t *ma)
88 free(ma->qsum); free(ma->bcnt);
89 free(ma->q2p); free(ma->pdg);
90 free(ma->phi); free(ma->alpha); free(ma->CMk);
91 free(ma->z); free(ma->zswap);
92 free(ma->afs); free(ma->afs1);
97 static int sum_err(int *n, const bam_pileup1_t **plp, mc_aux_t *ma)
100 memset(ma->qsum, 0, sizeof(int) * 4 * ma->n);
101 memset(ma->bcnt, 0, sizeof(int) * 4 * ma->n);
102 for (j = 0; j < ma->n; ++j) {
103 int *qsum = ma->qsum + j * 4;
104 int *bcnt = ma->bcnt + j * 4;
105 for (i = 0; i < n[j]; ++i) {
106 const bam_pileup1_t *p = plp[j] + i;
108 if (p->is_del || (p->b->core.flag&BAM_FUNMAP)) continue;
109 q = bam1_qual(p->b)[p->qpos];
110 if (p->b->core.qual < q) q = p->b->core.qual;
111 if (q < MC_MIN_QUAL) continue; // small qual
112 b = bam_nt16_nt4_table[(int)bam1_seqi(bam1_seq(p->b), p->qpos)];
113 if (b > 3) continue; // N
122 static void set_allele(int ref, mc_aux_t *ma)
124 int i, j, sum[4], tmp;
125 sum[0] = sum[1] = sum[2] = sum[3] = 0;
126 for (i = 0; i < ma->n; ++i)
127 for (j = 0; j < 4; ++j)
128 sum[j] += ma->qsum[i * 4 + j];
129 for (j = 0; j < 4; ++j) sum[j] = sum[j]<<2 | j;
130 for (i = 1; i < 4; ++i) // insertion sort
131 for (j = i; j > 0 && sum[j] < sum[j-1]; --j)
132 tmp = sum[j], sum[j] = sum[j-1], sum[j-1] = tmp;
133 ma->ref = sum[3]&3; ma->alt = sum[2]&3; ma->alt2 = -1;
134 if (ma->ref != ref) { // the best base is not ref
135 if (ref >= 0 && ref <= 3) { // ref is not N
136 if (ma->alt == ref) tmp = ma->ref, ma->ref = ma->alt, ma->alt = tmp; // then switch alt and ref
137 else ma->alt2 = ma->alt, ma->alt = ma->ref, ma->ref = ref; // then set ref as ref
138 } else ma->alt2 = ma->alt, ma->alt = ma->ref, ma->ref = sum[0]&3; // then set the weakest as ref
142 static void cal_pdg(mc_aux_t *ma)
145 for (j = 0; j < ma->n; ++j) {
146 int pi[3], *qsum, *bcnt;
147 double *pdg = ma->pdg + j * 3;
148 qsum = ma->qsum + j * 4;
149 bcnt = ma->bcnt + j * 4;
150 pi[1] = 3 * (bcnt[ma->ref] + bcnt[ma->alt]);
151 pi[0] = qsum[ma->ref];
152 pi[2] = qsum[ma->alt];
153 for (i = 0; i < 3; ++i)
154 pdg[i] = pi[i] > MC_MAX_SUMQ? MC_MAX_SUMQP : ma->q2p[pi[i]];
157 // this calculates the naive allele frequency and Nielsen's frequency
158 static double mc_freq0(const mc_aux_t *ma, double *_f)
161 double f, f_nielsen, w_sum;
163 for (i = cnt = 0, f = f_nielsen = w_sum = 0.; i < ma->n; ++i) {
164 int *bcnt = ma->bcnt + i * 4;
165 int x = bcnt[ma->ref] + bcnt[ma->alt];
169 f += (double)bcnt[ma->ref] / x;
170 p = (bcnt[ma->ref] - MC_AVG_ERR * x) / (1. - 2. * MC_AVG_ERR) / x;
171 w = 2. * x / (1. + x);
178 if (f_nielsen < 0.) f_nielsen = 0.;
179 if (f_nielsen > 1.) f_nielsen = 1.;
184 // f0 is the reference allele frequency
185 static double mc_freq_iter(double f0, const mc_aux_t *ma)
189 f3[0] = (1.-f0)*(1.-f0); f3[1] = 2.*f0*(1.-f0); f3[2] = f0*f0;
190 for (i = 0, f = 0.; i < ma->n; ++i) {
192 pdg = ma->pdg + i * 3;
193 f += (pdg[1] * f3[1] + 2. * pdg[2] * f3[2])
194 / (pdg[0] * f3[0] + pdg[1] * f3[1] + pdg[2] * f3[2]);
200 int mc_call_gt(const mc_aux_t *ma, double f0, int k)
203 double max, f3[3], *pdg = ma->pdg + k * 3;
205 f3[0] = (1.-f0)*(1.-f0); f3[1] = 2.*f0*(1.-f0); f3[2] = f0*f0;
206 for (i = 0, sum = 0.; i < 3; ++i)
207 sum += (g[i] = pdg[i] * f3[i]);
208 for (i = 0, max = -1., max_i = 0; i < 3; ++i) {
210 if (g[i] > max) max = g[i], max_i = i;
213 if (max < 1e-308) max = 1e-308;
214 q = (int)(-3.434 * log(max) + .499);
219 static void mc_cal_z(mc_aux_t *ma)
221 double *z[2], *tmp, *pdg;
226 z[0][0] = 1.; z[0][1] = z[0][2] = 0.;
227 for (j = 0; j < ma->n; ++j) {
228 int max = (j + 1) * 2;
230 pdg = ma->pdg + j * 3;
231 p[0] = pdg[0]; p[1] = 2. * pdg[1]; p[2] = pdg[2];
232 z[1][0] = p[0] * z[0][0];
233 z[1][1] = p[0] * z[0][1] + p[1] * z[0][0];
234 for (i = 2; i <= max; ++i)
235 z[1][i] = p[0] * z[0][i] + p[1] * z[0][i-1] + p[2] * z[0][i-2];
236 if (j < ma->n - 1) z[1][max+1] = z[1][max+2] = 0.;
237 // int k; for (k = 0; k <= max; ++k) printf("%d:%.3lg ", k, z[1][k]); putchar('\n');
238 tmp = z[0]; z[0] = z[1]; z[1] = tmp;
240 if (z[0] != ma->z) memcpy(ma->z, z[0], sizeof(double) * (2 * ma->n + 1));
243 static double mc_add_afs(mc_aux_t *ma)
246 long double sum = 0.;
247 memset(ma->afs1, 0, sizeof(double) * (ma->M + 1));
249 for (k = 0, sum = 0.; k <= ma->M; ++k)
250 sum += (long double)ma->alpha[k] * ma->z[k] / ma->CMk[k];
251 for (k = 0; k <= ma->M; ++k) {
252 ma->afs1[k] = ma->alpha[k] * ma->z[k] / ma->CMk[k] / sum;
253 if (isnan(ma->afs1[k]) || isinf(ma->afs1[k])) return -1.;
255 for (k = 0, sum = 0.; k <= ma->M; ++k) {
256 ma->afs[k] += ma->afs1[k];
257 sum += k * ma->afs1[k];
262 int mc_cal(int ref, int *n, const bam_pileup1_t **plp, mc_aux_t *ma, mc_rst_t *rst, int level)
265 memset(rst, 0, sizeof(mc_rst_t));
266 rst->f_em = rst->f_exp = -1.; rst->ref = rst->alt = -1;
268 tot = sum_err(n, plp, ma);
269 if (tot == 0) return 0; // no good bases
272 // set ref/major allele
273 rst->ref = ma->ref; rst->alt = ma->alt; rst->alt2 = ma->alt2;
274 // calculate naive and Nielsen's freq
275 rst->f_naive = mc_freq0(ma, &rst->f_nielsen);
277 double flast = rst->f_naive;
278 for (i = 0; i < MC_MAX_EM_ITER; ++i) {
279 rst->f_em = mc_freq_iter(flast, ma);
280 if (fabs(rst->f_em - flast) < MC_EM_EPS) break;
285 rst->f_exp = mc_add_afs(ma);
286 rst->p_ref = ma->afs1[ma->M];
291 void mc_dump_afs(mc_aux_t *ma)
294 fprintf(stderr, "[afs]");
295 for (k = 0; k <= ma->M; ++k)
296 fprintf(stderr, " %d:%.3lf", k, ma->afs[ma->M - k]);
297 fprintf(stderr, "\n");
298 memset(ma->afs, 0, sizeof(double) * (ma->M + 1));