def test_numeric_asymmetry(self):
matcher = ObjectListMatcher.for_sequence([0.6, 0.4])
matcher.should_store_similarity_matrix = True
a = [(3, 3), (8, 5), (9, 1)]
b = [(9, 8), (3, 2), (3, 4)]
# as (9, 8) is the best match for (9, 1), item (8, 5) will be matched to (3, 4)
assert matcher.get_indices(a, b) == [1, 2,
0], formatted_matrix(matcher)
matrix = matcher.similarity_matrix
# matrix[0] are the match scores of element (3, 3) in a to all elements in b
assert matrix[0][1] == matrix[0][2]
# (9, 1) is most similar to (9, 8) and second most similar to (3, 2)
assert matrix[2][0] > matrix[2][2]
assert matrix[2][1] > matrix[2][2]
# What happens here may seem confusing, but this is a result of the following
# asymmetry: the best match in b for (9, 1) is (9, 8), but the best match in a
# for (9, 8) isn't (9, 1), it's (8, 5). This can be seen by calculating the
# weighted delta between (9, 8) and each of them (smaller delta = more similar):
# delta to (9, 1): (9-9) * 0.6 + (8-1) * 0.4 = 2.8
# delta to (8, 5): (9-8) * 0.6 + (8-5) * 0.4 = 1.8
assert matcher.get_indices(b, a) == [1, 0,
2], formatted_matrix(matcher)
def test_match_a_to_nothing(self):
matcher = ObjectListMatcher.for_sequence([7, 1])
a = [('Great Song', 'Beach', 1), ('Great Sea', 'Low', 2)]
b = []
# When no b element could be matched to an a element, -1 is used.
assert matcher.get_indices(a, b) == [None, None]
def test_change_weights(self):
# same as in previous test
matcher = ObjectListMatcher.for_sequence([3, 1.5, 2])
a = [('cacc', 'cacc', 2), ('bacc', 'baca', 1)]
b = [('caba', 'bacc', 1), ('abaa', 'bcca', 2)]
matcher.update_attr_to_weight({lambda i: i[1]: 1})
assert matcher.get_indices(a, b) == [0, 1]
def test_nothing_to_match_b_to(self):
matcher = ObjectListMatcher.for_sequence([7, 1])
a = []
b = [('Great Song', 'Beach', 1), ('Great Sea', 'Low', 2)]
# As this returns the indices of b to match a, it always has the size of a.
assert matcher.get_indices(a, b) == []
assert matcher.get_indices([], []) == []
def test_other_now_barely_better(self):
matcher = ObjectListMatcher.for_sequence([3, 1.5, 2])
a = [('cacc', 'cacc', 2), ('bacc', 'baca', 1)]
b = [('caba', 'bacc', 1),
('abaa', 'bcca', 2)] # third element of first changed
assert matcher.get_indices(a, b) == [1, 0]
assert matcher.get_indices(a, b) == [1, 0]
assert matcher.get_indices(b, a) == [1, 0]
def test_double_weight(self):
matcher = ObjectListMatcher.for_sequence([4, 2])
a = [('Great Song', 'Law', 2), ('Night Mix', 'Beach', 1)]
b = [('Great Song', 'Beach', 1), ('Great Sea', 'Low', 2)]
assert matcher.get_indices(a, b) == [0, 1]
# changed "Law" to "Low"
a = [('Great Song', 'Low', 2), ('Night Mix', 'Beach', 1)]
assert matcher.get_indices(a, b) == [1, 0]
def test_numeric_if_both_good_match_current_order_preferred(self):
# we pre-normalized the weights for clarity here (they're always normalized)
matcher = ObjectListMatcher.for_sequence([0.6, 0.4])
a = [(3, 2), (3, 4)]
b = [(99, 99), (3, 3)]
# despite having the same delta to (3, 3), here (3, 2) should be preferred to
# (3, 4), as (3, 2) is a closer match (in terms of their indices)
assert matcher.get_indices(a, b) == [1, 0]
assert matcher.get_indices(b, a) == [1, 0]
def test_clear_match(self):
matcher = ObjectListMatcher.for_sequence([3, 1.5, 2])
a = [('cacc', 'cacc', 2), ('bacc', 'baca', 1)]
b = [('caba', 'bacc', 2), ('abaa', 'bcca', 2)]
assert matcher.get_indices(a, b) == [0, 1]
# test that repeating the same call doesn't change the result
assert matcher.get_indices(a, b) == [0, 1]
# in this case (same length), reversing arguments should result in the same list
assert matcher.get_indices(b, a) == [0, 1]
def test_should_go_through_every_attribute(self):
matcher = ObjectListMatcher.for_sequence([0.7, 0.3])
matcher.should_store_similarity_matrix = True
# There are undefeatable matches for the first attribute / weight here, and so
# by default the algorithm will not even check the second attribute.
a = [('a', -8), ('very clear', 0), ('way', 33), ('forward', 2)]
b = [('very clear', 33), ('forward', -1), ('a', 5), ('way', 2)]
assert matcher.get_indices(a, b) == [2, 0, 3, 1]
partial_matrix = matcher.similarity_matrix
matcher.should_go_through_every_attribute = True
# Result definitely shouldn't change
assert matcher.get_indices(a, b) == [2, 0, 3,
1], formatted_matrix(matcher)
# But in this case the matrix should have
assert matcher.similarity_matrix != partial_matrix, formatted_matrix(
matcher)
def test_all_the_same(self):
matcher = ObjectListMatcher.for_sequence([0.2, 0.7, 0.1])
x = (9, 9, 9)
assert matcher.get_indices([x, x, x], [x, x, x]) == [0, 1, 2]
def test_more_in_b(self):
matcher = ObjectListMatcher.for_sequence([7, 1])
a = [('Great Sea', 'Light', 2)]
b = [('Great Song', 'Beach', 1), ('Great Sea', 'Low', 2)]
assert matcher.get_indices(a, b) == [1]