计算间隔之间的值数 [英] Counting number of values between interval

问题描述

在python中，有没有一种有效的方法来计算数字数组在特定间隔之间的时间?我将使用的间隔数可能会变得很大

Is there any efficient way in python to count the times an array of numbers is between certain intervals? the number of intervals i will be using may get quite large

喜欢:

mylist = [4,4,1,18,2,15,6,14,2,16,2,17,12,3,12,4,15,5,17]

some function(mylist, startpoints):
   # startpoints = [0,10,20]
   count values in range [0,9]
   count values in range [10-19]

output = [9,10]

推荐答案

您将必须至少迭代一次该列表.

you will have to iterate the list at least once.

以下解决方案适用于实现比较的任何序列/间隔(<，>等)，并使用

The solution below works with any sequence/interval that implements comparision (<, >, etc) and uses bisect algorithm to find the correct point in the interval, so it is very fast.

它将适用于浮点数，文本或其他内容.只需传递一个序列和间隔列表即可.

It will work with floats, text, or whatever. Just pass a sequence and a list of the intervals.

from collections import defaultdict
from bisect import bisect_left

def count_intervals(sequence, intervals):
    count = defaultdict(int)
    intervals.sort()
    for item in sequence:
        pos = bisect_left(intervals, item)
        if pos == len(intervals):
            count[None] += 1
        else:
            count[intervals[pos]] += 1
    return count

data = [4,4,1,18,2,15,6,14,2,16,2,17,12,3,12,4,15,5,17]
print count_intervals(data, [10, 20])

将打印

defaultdict(<type 'int'>, {10: 10, 20: 9})

这意味着您有10个值<10和9个值< 20.

Meaning that you have 10 values <10 and 9 values <20.

这篇关于计算间隔之间的值数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！