Skip to content

bpo-41354: Add .ratio_min() function with minimum substring length option for matching score #30120

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
gi-ba-bu wants to merge 1 commit into from
Closed

bpo-41354: Add .ratio_min() function with minimum substring length option for matching score #30120

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 26 additions & 0 deletions Lib/difflib.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -618,7 +618,33 @@ def ratio(self):

matches = sum(triple[-1] for triple in self.get_matching_blocks())
return _calculate_ratio(matches, len(self.a) + len(self.b))


# NEW FUNCTION: ratio_min
def ratio_min(self,m):
"""Return a measure of the sequences' similarity (float in [0,1]).
Where T is the total number of elements in both sequences, and
M_min is the number of matches with every single match has length at least m, this is 2.0*M_min / T.
Note that this is 1 if the sequences are identical, and 0 if
they have no substring of length m or more in common.
.ratio_min() is similar to .ratio().
.ratio_min(1) is equivalent to .ratio().

>>> s = SequenceMatcher(None, "abcd", "bcde")
>>> s.ratio_min(1)
0.75
>>> s.ratio_min(2)
0.75
>>> s.ratio_min(3)
0.75
>>> s.ratio_min(4)
0.0
"""

matches = sum(triple[-1] for triple in self.get_matching_blocks() if triple[-1] >=m)
return _calculate_ratio(matches, len(self.a) + len(self.b))


def quick_ratio(self):
"""Return an upper bound on ratio() relatively quickly.

Expand Down