纯Python：
from __future__ import division
def mean(a):
return sum(a) / len(a)
a = [[240, 240, 239],
[250, 249, 237],
[242, 239, 237],
[240, 234, 233]]
print map(mean, zip(*a))
印刷
[243.0, 240.5, 236.5]
NumPy：
a = numpy.array([[240, 240, 239],
[250, 249, 237],
[242, 239, 237],
[240, 234, 233]])
print numpy.mean(a, axis=0)
Python 3：
from statistics import mean
a = [[240, 240, 239],
[250, 249, 237],
[242, 239, 237],
[240, 234, 233]]
print(*map(mean, zip(*a)))
602392714
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