extern void invcomp_dna(
char *sequence, /* DNA sequence */
long length /* length of sequence */
)
{
char *sl = sequence; /* left end of sequence */
char *sr = sequence + length - 1; /* right end of sequence */
for (; sl<=sr; sl++, sr--) {
char tmp = comp_dna(*sl);
*sl = comp_dna(*sr);
*sr = tmp;
}
} /* invcomp_dna */
static void average_rc(
BOOLEAN add_x, /* add x-tuples if TRUE */
double *a_p, /* tuple->prob assoc. array */
int n, /* widest tuple */
char *tuple, /* call with "" */
int tuplew, /* tuple width; call with 0 */
const char *alpha /* alphabet */
)
{
int i, j;
char *t = NULL, *rc = NULL; /* tuple and rc-tuple */
int ti, rci; /* index of tuple */
if (n==0) return; /* everything is OK */
Resize(t, tuplew+2, char);
Resize(rc, tuplew+2, char);
for(i=0; alpha[i+add_x]; i++) { /* ignore last letter (X) */
/* append letter to tuple */
strcpy(t, tuple); t[tuplew] = alpha[i]; t[tuplew+1] = '\0';
/* make reverse complement of tuple */
for (j=0; j<=tuplew; j++) rc[j] = comp_dna(t[tuplew-j]);
rc[tuplew+1] = '\0';
/* get tuple and rc indices */
ti = s2i(t); /* index of tuple */
rci = s2i(rc); /* index of reverse complement*/
/* average their probabilites */
a_p[ti] = a_p[rci] = (a_p[ti] + a_p[rci]) / 2.0;
/* recur */
average_rc(add_x, a_p, n-1, t, tuplew+1, alpha);
} /* letter */
myfree(t);
myfree(rc);
return;
} /* average_rc */