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// Copyright 2013 Calvin Morrison
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
const unsigned char alpha[256] =
{5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 0, 5, 1, 5, 5, 5, 2, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 0, 5, 1, 5, 5, 5, 2,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 3, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5};
const char reverse_alpha[4] = { 'A', 'C', 'G', 'T' };
unsigned long long pow_four(unsigned long long x) {
return (unsigned long long)1 << (x * 2);
}
// convert a string of k-mer size base-4 values into a
// base-10 index
inline unsigned long num_to_index(const char *str, const int kmer, const long error_pos, long long *current_position) {
int i = 0;
unsigned long out = 0;
unsigned long multiply = 1;
for(i = kmer - 1; i >= 0; i--){
if(str[i] == 5) {
current_position += i;
return error_pos;
}
out += str[i] * multiply;
multiply = multiply << 2;
}
return out;
}
// return the number of loaded elements
unsigned long long load_specific_mers_from_file(char *fn, unsigned int kmer, size_t width, size_t *arr) {
FILE *fh;
size_t arr_pos = 0;
char line[64];
fh = fopen(fn, "r");
if(fh == NULL) {
fprintf(stderr, "Error opening %s - %s\n", fn, strerror(errno));
exit(EXIT_FAILURE);
}
while (fgets(line, sizeof(line), fh) != NULL) {
size_t i;
size_t len;
len = strlen(line);
if(len == 0)
continue;
len--;
line[len] = '\0';
if(len != kmer) {
fprintf(stderr, "SKIPPING: '%s' is not length %u\n", line, kmer);
continue;
}
for(i = 0; i < len; i++) {
line[i] = alpha[(int)line[i]];
}
size_t mer = num_to_index(line, kmer, width, NULL);
if(mer == width) {
fprintf(stderr, "SKIPPING: '%s' is a unrecognized mer\n", line);
continue;
}
else {
arr[arr_pos] = mer;
arr_pos++;
}
}
fclose(fh);
return arr_pos;
}
// convert an index back into a kmer string
char *index_to_kmer(unsigned long long index, long kmer) {
size_t i = 0;
size_t j = 0;
char *num_array = calloc(kmer, sizeof(char));
char *ret = calloc(kmer + 1, sizeof(char));
if(ret == NULL)
exit(EXIT_FAILURE);
// this is the core of the conversion. modulus 4 for base 4 conversion
while (index != 0) {
num_array[i] = index % 4;
index /= 4;
i++;
}
// for our first few nmers, like AAAAA, the output would only be "A" instead
// of AAAAA so we prepend it
for(j = 0; j < (kmer - i); j++)
ret[j] = 'A';
// our offset for how many chars we prepended
int offset = j;
// save i so we can print it
size_t start = i ;
// decrement i by 1 to reverse the last i++
i--;
j = 0;
// reverse the array, as j increases, decrease i
for(j = 0; j < start; j++, i--)
ret[j + offset] = reverse_alpha[(int)num_array[i]];
// set our last character to the null termination byte
ret[kmer + 1] = '\0';
free(num_array);
return ret;
}
// Strip out any character 'c' from char array 's'
size_t strnstrip(char *s, int c, size_t len) {
size_t i = 0;
size_t j = 0;
for(i = 0; i < len; i++) {
if(s[i] != c) {
if(j != i)
s[j] = s[i];
j++;
}
}
s[j] = '\0';
return j;
}
unsigned long long * get_kmer_counts_from_file(FILE *fh, const unsigned int kmer) {
char *line = NULL;
size_t len = 0;
ssize_t read;
long long i = 0;
long long position = 0;
// width is 4^kmer
// there's a sneaky bitshift to avoid pow dependency
const unsigned long width = pow_four(kmer);
// malloc our return array
unsigned long long * counts = calloc((width+ 1), sizeof(unsigned long long));
if(counts == NULL) {
fprintf(stderr, strerror(errno));
exit(EXIT_FAILURE);
}
while ((read = getdelim(&line, &len, '>', fh)) != -1) {
size_t k;
char *seq;
size_t seq_length;
// find our first \n, this should be the end of the header
seq = strchr(line, '\n');
if(seq == NULL)
continue;
// point to one past that.
seq = seq + 1;
// strip out all other newlines to handle multiline sequences
strnstrip(seq, '\n', strlen(seq));
seq_length = strlen(seq);
// relace A, C, G and T with 0, 1, 2, 3 respectively
// everything else is 5
for(k = 0; k < seq_length; k++)
seq[k] = alpha[(int)seq[k]];
// loop through our seq to process each k-mer
for(position = 0; position < (signed)(seq_length - kmer + 1); position++) {
unsigned long long mer = 0;
unsigned long long multiply = 1;
// for each char in the k-mer check if it is an error char
for(i = position + kmer - 1; i >= position; i--){
if(seq[i] == 5) {
mer = width;
position = i;
goto next;
}
// multiply this char in the mer by the multiply
// and bitshift the multiply for the next round
mer += seq[i] * multiply;
multiply = multiply << 2;
}
// use this point to get mer of our loop
next:
// bump up the mer value in the counts array
counts[mer]++;
}
}
free(line);
fclose(fh);
return counts;
}
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