在python中将numpy中的数组展平的正确有效的方法? [英] correct and efficient way to flatten array in numpy in python?

问题描述

我有:

a = array([[1,2,3],[4,5,6]])

我想将其展平，将两个内部列表合并为一个平面数组条目.我可以:

array(list(flatten(a)))

但由于列表转换，这似乎效率低下(我想以数组而不是生成器结束.)

此外，如何将其推广到这样的数组:

b = array([[[1,2,3],[4,5,6]], [[10,11,12],[13,14,15]]])

结果应该在哪里:

b = array([[1,2,3,4,5,6],[10,11,12,13,14,15]])

是否有内置/高效的 numpy/scipy 运算符?谢谢.

解决方案

您可以使用 reshape 方法.

<预><代码>>>>导入 numpy>>>b = numpy.array([[[1,2,3],[4,5,6]], [[10,11,12],[13,14,15]]])>>>b.reshape([2, 6])数组([[ 1, 2, 3, 4, 5, 6],[10, 11, 12, 13, 14, 15]])

I have:

a = array([[1,2,3],[4,5,6]])

and I'd like to flatten it, joining the two inner lists into one flat array entry. I can do:

array(list(flatten(a)))

but that seems inefficient due to the list cast (I want to end up with an array and not a generator.)

Also, how can this be generalized to an array like this:

b = array([[[1,2,3],[4,5,6]], [[10,11,12],[13,14,15]]])

where the result should be:

b = array([[1,2,3,4,5,6],
           [10,11,12,13,14,15]])

are there builtin/efficient numpy/scipy operators for this? thanks.

解决方案

You can use the reshape method.

>>> import numpy
>>> b = numpy.array([[[1,2,3],[4,5,6]], [[10,11,12],[13,14,15]]])
>>> b.reshape([2, 6])
array([[ 1,  2,  3,  4,  5,  6],
       [10, 11, 12, 13, 14, 15]])

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