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from py_stringmatching.similarity_measure.cython.cython_utils import int_max_two
import numpy as np
cimport numpy as np
#Cython functions to compute the Jaro score
def jaro(unicode string1, unicode string2):
"""Computes the Jaro score between two strings.
Args:
string1,string2 (str): Input strings.
Returns:
Jaro distance score (float).
"""
cdef int len_str1 = len(string1), len_str2 = len(string2)
cdef int max_len = int_max_two(len_str1, len_str2)
cdef int search_range = (max_len // 2) - 1
if search_range < 0:
search_range = 0
# populating numpy arrays of length as each string with zeros
cdef int[:] flags_s1 = np.zeros(len_str1, dtype=np.int32)
cdef int[:] flags_s2 = np.zeros(len_str2, dtype=np.int32)
cdef int common_chars = 0, low = 0, high = 0, i = 0, j = 0
# Finding the number of common characters in two strings
for i from 0 <= i < len_str1:
low = i - search_range if i > search_range else 0
high = i + search_range if i + search_range < len_str2 else len_str2 - 1
for j from low <= j < (high + 1):
if flags_s2[j] == 0 and string2[j] == string1[i]:
flags_s1[i] = flags_s2[j] = 1
common_chars += 1
break
if common_chars == 0:
return 0
cdef int trans_count = 0, k = 0
# Finding the number of transpositions and Jaro distance
for i from 0 <= i < len_str1:
if flags_s1[i] == 1:
for j from k <= j < len_str2:
if flags_s2[j] == 1:
k = j + 1
break
if string1[i] != string2[j]:
trans_count += 1
trans_count /= 2
cdef float score = (float(common_chars) / len_str1 + float(common_chars) / len_str2 +
(float(common_chars) - trans_count) / float(common_chars)) / 3
return score
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