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gh-142939: difflib.get_close_matches performance #142940

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gh-142939: difflib.get_close_matches performance #142940

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16 changes: 9 additions & 7 deletions Lib/difflib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -638,15 +638,15 @@ def quick_ratio(self):
# avail[x] is the number of times x appears in 'b' less the
# number of times we've seen it in 'a' so far ... kinda
avail = {}
availhas, matches = avail.__contains__, 0
matches = 0
for elt in self.a:
if availhas(elt):
if elt in avail:
numb = avail[elt]
else:
numb = fullbcount.get(elt, 0)
avail[elt] = numb - 1
if numb > 0:
matches = matches + 1
matches += 1
return _calculate_ratio(matches, len(self.a) + len(self.b))

def real_quick_ratio(self):
Expand Down Expand Up @@ -702,10 +702,12 @@ def get_close_matches(word, possibilities, n=3, cutoff=0.6):
s.set_seq2(word)
for x in possibilities:
s.set_seq1(x)
if s.real_quick_ratio() >= cutoff and \
s.quick_ratio() >= cutoff and \
s.ratio() >= cutoff:
result.append((s.ratio(), x))
if s.real_quick_ratio() < cutoff or s.quick_ratio() < cutoff:
continue

ratio = s.ratio()
if ratio >= cutoff:
result.append((ratio, x))

# Move the best scorers to head of list
result = _nlargest(n, result)
Expand Down
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