Calculating arithmetic mean (average) in Python

2018-06-07 08:13:54

Python中是否有内置或标准库方法来计算数字列表的算术平均值（平均值）？

I am not aware of anything in the standard library. However, you could use something like:

def mean(numbers):
    return float(sum(numbers)) / max(len(numbers), 1)

>>> mean([1,2,3,4])
2.5
>>> mean([])
0.0

In numpy, there's numpy.mean() .

NumPy has a numpy.mean which is an arithmetic mean. Usage is as simple as this:

>>> import numpy
>>> a = [1, 2, 4]
>>> numpy.mean(a)
2.3333333333333335

In Python 3.4, there is a new statistics module. You can now use statistics.mean :

import statistics
print(statistics.mean([1,2,4])) # 2.3333333333333335

For 3.1-3.3 users, the original version of the module is available on PyPI under the name stats . Just change statistics to stats .

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