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bpo-4356: Add key function support to the bisect module (GH-20556)

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Raymond Hettinger 2020-10-19 22:04:01 -07:00 • committed by GitHub
parent de73d432bb
commit 871934d4cf
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7 changed files with 333 additions and 93 deletions
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66
Lib/bisect.py
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@ -1,6 +1,7 @@
"""Bisection algorithms."""
def insort_right(a, x, lo=0, hi=None):
def insort_right(a, x, lo=0, hi=None, *, key=None):
"""Insert item x in list a, and keep it sorted assuming a is sorted.
If x is already in a, insert it to the right of the rightmost x.
@ -8,11 +9,14 @@ def insort_right(a, x, lo=0, hi=None):
Optional args lo (default 0) and hi (default len(a)) bound the
slice of a to be searched.
"""
lo = bisect_right(a, x, lo, hi)
if key is None:
lo = bisect_right(a, x, lo, hi)
else:
lo = bisect_right(a, key(x), lo, hi, key=key)
a.insert(lo, x)
def bisect_right(a, x, lo=0, hi=None):
def bisect_right(a, x, lo=0, hi=None, *, key=None):
"""Return the index where to insert item x in list a, assuming a is sorted.
The return value i is such that all e in a[:i] have e <= x, and all e in
@ -27,14 +31,26 @@ def bisect_right(a, x, lo=0, hi=None):
raise ValueError('lo must be non-negative')
if hi is None:
hi = len(a)
while lo < hi:
mid = (lo+hi)//2
# Use __lt__ to match the logic in list.sort() and in heapq
if x < a[mid]: hi = mid
else: lo = mid+1
# Note, the comparison uses "<" to match the
# __lt__() logic in list.sort() and in heapq.
if key is None:
while lo < hi:
mid = (lo + hi) // 2
if x < a[mid]:
hi = mid
else:
lo = mid + 1
else:
while lo < hi:
mid = (lo + hi) // 2
if x < key(a[mid]):
hi = mid
else:
lo = mid + 1
return lo
def insort_left(a, x, lo=0, hi=None):
def insort_left(a, x, lo=0, hi=None, *, key=None):
"""Insert item x in list a, and keep it sorted assuming a is sorted.
If x is already in a, insert it to the left of the leftmost x.
@ -43,11 +59,13 @@ def insort_left(a, x, lo=0, hi=None):
slice of a to be searched.
"""
lo = bisect_left(a, x, lo, hi)
if key is None:
lo = bisect_left(a, x, lo, hi)
else:
lo = bisect_left(a, key(x), lo, hi, key=key)
a.insert(lo, x)
def bisect_left(a, x, lo=0, hi=None):
def bisect_left(a, x, lo=0, hi=None, *, key=None):
"""Return the index where to insert item x in list a, assuming a is sorted.
The return value i is such that all e in a[:i] have e < x, and all e in
@ -62,13 +80,25 @@ def bisect_left(a, x, lo=0, hi=None):
raise ValueError('lo must be non-negative')
if hi is None:
hi = len(a)
while lo < hi:
mid = (lo+hi)//2
# Use __lt__ to match the logic in list.sort() and in heapq
if a[mid] < x: lo = mid+1
else: hi = mid
# Note, the comparison uses "<" to match the
# __lt__() logic in list.sort() and in heapq.
if key is None:
while lo < hi:
mid = (lo + hi) // 2
if a[mid] < x:
lo = mid + 1
else:
hi = mid
else:
while lo < hi:
mid = (lo + hi) // 2
if key(a[mid]) < x:
lo = mid + 1
else:
hi = mid
return lo
# Overwrite above definitions with a fast C implementation
try:
from _bisect import *