python标准库学习5 ---bisect — Array bisection algorithm

最新推荐文章于 2025-08-11 22:22:04 发布

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最新推荐文章于 2025-08-11 22:22:04 发布

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原文链接：http://www.cnblogs.com/rollenholt/archive/2011/11/26/2264244.html

本文介绍Python标准库中的bisect模块用法，通过示例展示了如何利用bisect进行有序列表的查找与插入操作，并提供了自定义查找函数，帮助读者理解和应用bisect模块解决实际问题。

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#coding=utf-8

import bisect

list=[1,2,3,4,6,7,8,9]   #假定list已经排序
print bisect.bisect_left(list,5)  #返回5应该插入的索引位置

print bisect.bisect_right(list, 5)

print bisect.bisect(list,5)

bisect.insort_left(list, 5, 0, len(list))
print list

bisect.insort_right(list, 5)
print list

def index(a, x):
    'Locate the leftmost value exactly equal to x'
    i = bisect_left(a, x)
    if i != len(a) and a[i] == x:
        return i
    raise ValueError

def find_lt(a, x):
    'Find rightmost value less than x'
    i = bisect_left(a, x)
    if i:
        return a[i-1]
    raise ValueError

def find_le(a, x):
    'Find rightmost value less than or equal to x'
    i = bisect_right(a, x)
    if i:
        return a[i-1]
    raise ValueError

def find_gt(a, x):
    'Find leftmost value greater than x'
    i = bisect_right(a, x)
    if i != len(a):
        return a[i]
    raise ValueError

def find_ge(a, x):
    'Find leftmost item greater than or equal to x'
    i = bisect_left(a, x)
    if i != len(a):
        return a[i]
raise ValueError

>>> def grade(score, breakpoints=[60, 70, 80, 90], grades='FDCBA'):
...     i = bisect(breakpoints, score)
...     return grades[i]
...
>>> [grade(score) for score in [33, 99, 77, 70, 89, 90, 100]]
['F', 'A', 'C', 'C', 'B', 'A', 'A']

>>> data = [('red', 5), ('blue', 1), ('yellow', 8), ('black', 0)]
>>> data.sort(key=lambda r: r[1])
>>> keys = [r[1] for r in data]         # precomputed list of keys
>>> data[bisect_left(keys, 0)]
('black', 0)
>>> data[bisect_left(keys, 1)]
('blue', 1)
>>> data[bisect_left(keys, 5)]
('red', 5)
>>> data[bisect_left(keys, 8)]
('yellow', 8)

转载于:https://www.cnblogs.com/rollenholt/archive/2011/11/26/2264244.html