float
distance_jaccard(struct sr_thread *thread1,
struct sr_thread *thread2)
{
assert(thread1->type == thread2->type);
int intersection_size = 0, set1_size = 0, set2_size = 0;
for (struct sr_frame *curr_frame = sr_thread_frames(thread1);
curr_frame;
curr_frame = sr_frame_next(curr_frame))
{
if (distance_jaccard_frames_contain(
sr_frame_next(curr_frame),
curr_frame))
{
continue; // not last, skip
}
++set1_size;
if (distance_jaccard_frames_contain(
sr_thread_frames(thread2),
curr_frame))
{
++intersection_size;
}
}
for (struct sr_frame *curr_frame = sr_thread_frames(thread2);
curr_frame;
curr_frame = sr_frame_next(curr_frame))
{
if (distance_jaccard_frames_contain(
sr_frame_next(curr_frame),
curr_frame))
{
continue; // not last, skip
}
++set2_size;
}
int union_size = set1_size + set2_size - intersection_size;
if (!union_size)
return 0.0;
float j_distance = 1.0 - intersection_size / (float)union_size;
if (j_distance < 0.0)
j_distance = 0.0;
return j_distance;
}
PyObject *
frames_to_python_list(struct sr_thread *thread, PyTypeObject *frame_type)
{
PyObject *result = PyList_New(0);
if (!result)
return NULL;
struct sr_frame *frame = sr_thread_frames(thread);
struct sr_py_base_frame *item;
while (frame)
{
item = PyObject_New(struct sr_py_base_frame, frame_type);
if (!item)
return PyErr_NoMemory();
/* XXX may need to initialize item further */
/* It would be a good idea to have a common code that is executed each
* time new object (e.g. via __new__ or _dup) is created so that we
* don't miss setting some attribute. As opposed to using PyObject_New
* directly. */
item->frame = frame;
if (PyList_Append(result, (PyObject *)item) < 0)
return NULL;
frame = sr_frame_next(frame);
}
return result;
}
static bool
distance_jaccard_frames_contain(struct sr_frame *haystack,
struct sr_frame *needle)
{
while (haystack)
{
// Checking if functions are the same but not both "??".
if (!sr_frame_cmp_distance(haystack, needle))
return true;
haystack = sr_frame_next(haystack);
}
return false;
}
float
distance_jaro_winkler(struct sr_thread *thread1,
struct sr_thread *thread2)
{
assert(thread1->type == thread2->type);
int frame1_count = sr_thread_frame_count(thread1);
int frame2_count = sr_thread_frame_count(thread2);
if (frame1_count == 0 && frame2_count == 0)
return 1.0;
int max_frame_count = frame2_count;
if (max_frame_count < frame1_count)
max_frame_count = frame1_count;
int prefix_len = 0;
bool still_prefix = true;
float trans_count = 0, match_count = 0;
struct sr_frame *curr_frame = sr_thread_frames(thread1);
for (int i = 1; curr_frame; ++i)
{
bool match = false;
struct sr_frame *curr_frame2 = sr_thread_frames(thread2);
for (int j = 1; !match && curr_frame2; ++j)
{
/* Whether the prefix continues to be the same for both
* threads or not.
*/
if (i == j && 0 != sr_frame_cmp_distance(curr_frame, curr_frame2))
still_prefix = false;
/* Getting a match only if not too far away from each
* other and if functions aren't both unpaired unknown
* functions.
*/
if (abs(i - j) <= max_frame_count / 2 - 1 &&
0 == sr_frame_cmp_distance(curr_frame, curr_frame2))
{
match = true;
if (i != j)
++trans_count; // transposition in place
}
curr_frame2 = sr_frame_next(curr_frame2);
}
if (still_prefix)
++prefix_len;
if (match)
++match_count;
curr_frame = sr_frame_next(curr_frame);
}
trans_count /= 2;
if (prefix_len > 4)
prefix_len = 4;
if (0 == match_count)
return 0; // so as not to divide by 0
float dist_jaro = (match_count / (float)frame1_count +
match_count / (float)frame2_count +
(match_count - trans_count) / match_count) / 3;
/* How much weight we give to having common prefixes
* (always k < 0.25).
*/
float k = 0.2;
float dist = dist_jaro + (float)prefix_len * k * (1 - dist_jaro);
return dist;
}
float
distance_levenshtein(struct sr_thread *thread1,
struct sr_thread *thread2,
bool transposition)
{
assert(thread1->type == thread2->type);
int frame_count1 = sr_thread_frame_count(thread1);
int frame_count2 = sr_thread_frame_count(thread2);
int max_frame_count = frame_count2;
if (max_frame_count < frame_count1)
max_frame_count = frame_count1;
/* Avoid division by zero in case we get two empty threads */
if (max_frame_count == 0)
return 0.0;
int m = frame_count1 + 1;
int n = frame_count2 + 1;
// store only two last rows and columns instead of whole 2D array
SR_ASSERT(n <= SIZE_MAX - 1);
SR_ASSERT(m <= SIZE_MAX - (n + 1));
int *dist = sr_malloc_array(sizeof(int), m + n + 1);
int *dist1 = sr_malloc_array(sizeof(int), m + n + 1);
// first row and column having distance equal to their position
for (int i = m; i > 0; --i)
dist[m - i] = i;
for (int i = 0; i <= n; ++i)
dist[m + i] = i;
struct sr_frame *curr_frame2 = sr_thread_frames(thread2);
struct sr_frame *prev_frame = NULL;
struct sr_frame *prev_frame2 = NULL;
for (int j = 1; curr_frame2; ++j)
{
struct sr_frame *curr_frame = sr_thread_frames(thread1);
for (int i = 1; curr_frame; ++i)
{
int l = m + j - i;
int dist2 = dist1[l];
dist1[l] = dist[l];
int cost;
/*similar characters have distance equal to the previous
one diagonally, "??" functions aren't taken as
similar */
if (0 == sr_frame_cmp_distance(curr_frame, curr_frame2))
cost = 0;
else
{
// different ones takes the lowest value of all
// previous distances
cost = 1;
dist[l] += 1;
if (dist[l] > dist[l - 1] + 1)
dist[l] = dist[l - 1] + 1;
if (dist[l] > dist[l + 1] + 1)
dist[l] = dist[l + 1] + 1;
}
/*checking for transposition of two characters in both ways
taking into account that "??" functions are not similar*/
if (transposition &&
(i >= 2 && j >= 2 && dist[l] > dist2 + cost &&
0 == sr_frame_cmp_distance(curr_frame, prev_frame2) &&
0 == sr_frame_cmp_distance(prev_frame, curr_frame2)))
{
dist[l] = dist2 + cost;
}
prev_frame = curr_frame;
curr_frame = sr_frame_next(curr_frame);
}
prev_frame2 = curr_frame2;
curr_frame2 = sr_frame_next(curr_frame2);
}
int result = dist[n];
free(dist);
free(dist1);
return (float)result / max_frame_count;
}