数字列表的平均值，以字符串形式存储在Python列表中 [英] Average of a list of numbers, stored as strings in a Python list

问题描述

我想计算python中多个列表的平均值.这些列表包含数字作为字符串.空字符串不为零，表示缺少值.

I want to calculate the average value of several lists in python. These lists contain numbers as strings. Empty string isn't zero, it means a missing value.

我能想到的最好的就是这个.是否有一个更优雅，更简洁的&有效的编写方式?

The best I could come up with is this. Is there a more elegant, succinct & efficient way of writing this?

num    = ['1', '2', '', '6']
total  = sum([int(n) if n else 0 for n in num])
length = sum([1 if n else 0 for n in num])
ave    = float(total)/length if length > 0 else '-'

P.S.我使用的是Python 2.7.x，但欢迎使用Python 3.x的食谱

P.S. I'm using Python 2.7.x but recipes for Python 3.x are welcome

推荐答案

num = ['1', '2', '', '6']
L = [int(n) for n in num if n]
ave = sum(L)/float(len(L)) if L else '-'

或

num = ['1', '2', '', '6']
L = [float(n) for n in num if n]
avg = sum(L)/len(L) if L else '-'

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