检查给定浮点数在列表中的哪个浮点数之间 [英] Check between which floats in a list a given float falls
问题描述
我有一个看起来像这样的列表:
I have a list that looks like this:
# Ordered list.
a = [0.1, 0.3, 0.4, 0.5, 0.6, 0.7, 0.9]
我需要遍历如下所示的浮点列表:
I need to iterate through a list of floats that looks like this:
# Not ordered list.
b = [0.12, 0.53, 0.30, 0.03, 0.77, 0.62, 0.98, 0.01, 0.42, 0.33, 1.3]
检查列表b
中每个元素在列表a
中的哪些元素之间,并返回a
中的元素的索引(在右侧).例如,对于上方的列表b
,结果将如下所示:
check between which elements in list a
each element in list b
falls, and return the index of the element in a
(to the right). For example, for the list b
above the results would look like:
indxs = [1, 4, 2, 0, 6, 5, 7, 0, 3, 2, 7]
(注意索引7指向与> max(a)
相关联的a
中的一个额外元素)
(notice the index 7 which points to an extra element in a
associated to > max(a)
)
我可以通过一个如下所示的精致的for/if
循环来做到这一点,但是我想知道是否有一种我可能不知道的函数可能更简单的方法(欢迎使用numpy
/scipy
函数)
I could do this with a rather elaborated for/if
loop as shown below, but I was wondering if there might be an easier way with some function I might not be aware of (numpy
/scipy
functions are welcomed)
MWE:
indxs = []
for b_el in b:
# Check if float is to the right of max(a)
if b_el > max(a):
indxs.append(len(a))
else:
for a_el in a:
if b_el < a_el:
indxs.append(a.index(a_el))
break
elif b_el == a_el:
indxs.append(a.index(a_el) + 1)
break
推荐答案
普通的Python解决方案是 bisect
模块,该模块具有用于二进制搜索的几种功能:
The ordinary Python solution is the bisect
module, which has several functions for binary search:
>>> [bisect.bisect(a, x) for x in b]
[1, 4, 2, 0, 6, 5, 7, 0, 3, 2, 7]
NumPy解决方案是 numpy.searchsorted
,其作用大致相同:
The NumPy solution is numpy.searchsorted
, which does much the same:
>>> numpy.searchsorted(a, b, side='right')
array([1, 4, 2, 0, 6, 5, 7, 0, 3, 2, 7], dtype=int64)
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