Python：如何获取间隔所属的浮点值？

Question

我有一些像（0,1），[1,2），...，[9,10）之类的间隔。我想知道一个浮点值， eg 3.75 ，属于哪个间隔。我所做的是使左边界列表[0,1,...,9]和右边界列表[1,2,...,10] 。 我会在左边界找到比第一个大3.75的值3然后在右边界找到比第一个小3.75值4然后3.75属于区间[3,4）。找到3.75属于哪个区间的方法？

Answer 1

仅存储一个边界列表就足够了。 您可以使用bisect_right找到间隔的左边界索引，然后index + 1是右边界：

import bisect

def find(num, boundaries):
    if boundaries[0] < num < boundaries[-1]:
        index = bisect.bisect_right(boundaries, num)
        return boundaries[index - 1], boundaries[index]
    return None

b = range(11)
CASES = [3.75, 0, 10, 5, 0.1, 9.9, 11, -1, 6.7]

for n in CASES:
    print('{} belongs to group {}'.format(n, find(n, b)))

输出：

3.75 belongs to group (3, 4)
0 belongs to group None
10 belongs to group None
5 belongs to group (5, 6)
0.1 belongs to group (0, 1)
9.9 belongs to group (9, 10)
11 belongs to group None
-1 belongs to group None
6.7 belongs to group (6, 7)

Answer 2

您也可以尝试使用Python数学库中的floor（）和ceil（）函数来解决您的问题。

import math
lb = [0,1,2,3,4,5,6,7,8,9]
ub = [1,2,3,4,5,6,7,8,9,10]

inp = raw_input('Enter a number : ')
num = float(inp)

term = [[x, y] for x, y in zip(lb, ub) if int(math.floor(num)) == x and        int(math.ceil(num)) == y] 
if term == []:
    print str(num) + ' does not belong to any specified interval'
else:
    print str(num) + ' belongs to the interval ' + str(term[0])