[英]How to iterate over columns of a matrix?
In python if a define: 在python中如果定义:
a = arange(9).reshape(3,3)
as a 3x3 matrix and iterate: 作为3x3矩阵并迭代:
for i in a:
It'll iterate over the matrix's rows. 它将迭代矩阵的行。 Is there any way to iterate over columns?
有没有办法迭代列?
How about 怎么样
for i in a.transpose():
or, shorter: 或者,更短:
for i in a.T:
This may look expensive but is in fact very cheap (it returns a view onto the same data, but with the shape and stride attributes permuted). 这可能看起来很昂贵,但实际上非常便宜(它将视图返回到相同的数据上,但其形状和步幅属性被置换)。
Assuming that a
is a well formed matrix, you could try something like: 假设
a
是一个格式良好的矩阵,您可以尝试以下方法:
b = zip(*a)
for index in b:
...
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