在Numpy中转置一维数组而不转换为矩阵 [英] Transpose a 1-dimensional array in Numpy without casting to matrix

问题描述

我的目标是将行向量变成列向量，反之亦然. numpy.ndarray.transpose 说:

My goal is to to turn a row vector into a column vector and vice versa. The documentation for numpy.ndarray.transpose says:

对于一维数组，这无效. (要在列向量和行向量之间切换，请先将一维数组转换为矩阵对象.)

For a 1-D array, this has no effect. (To change between column and row vectors, first cast the 1-D array into a matrix object.)

但是，当我尝试此操作时:

However, when I try this:

my_array = np.array([1,2,3])
my_array_T = np.transpose(np.matrix(myArray))

我确实得到了所需的结果，尽管是矩阵形式(matrix([[66],[640],[44]]))，但我也得到了这个警告:

I do get the wanted result, albeit in matrix form (matrix([[66],[640],[44]])), but I also get this warning:

PendingDeprecationWarning :建议不要使用矩阵子类来表示矩阵或处理线性代数(请参见

PendingDeprecationWarning: the matrix subclass is not the recommended way to represent matrices or deal with linear algebra (see https://docs.scipy.org/doc/numpy/user/numpy-for-matlab-users.html). Please adjust your code to use regular ndarray.

my_array_T = np.transpose(np.matrix(my_array))

那我该如何正确换位ndarray?

推荐答案

1D数组本身一旦转置，与Matlab相反，在Matlab中，一维数组不存在且至少为2D.

A 1D array is itself once transposed, contrary to Matlab where a 1D array doesn't exist and is at least 2D.

您要重塑它:

my_array.reshape(-1, 1)

或者:

my_array.reshape(1, -1)

取决于要使用的向量类型(列向量还是行向量).

Depending on what kind of vector you want (column or row vector).

-1类似于广播，使用了所有可能的元素，并且1创建了第二个所需的尺寸.

The -1 is a broadcast-like, using all possible elements, and the 1 creates the second required dimension.

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