numpy基础——matrix.transpose() 和 matrix.getA()

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本文介绍了numpy库中matrix对象的getA方法，它将matrix转换为ndarray对象，等价于np.asarray(self)。同时讨论了transpose函数，用于进行矩阵转置，1-D数组不受影响，2-D数组则是常规的转置操作，对于n-D数组，可以指定轴的排列方式。附带了相关示例。

numpy.matrix.getA

matrix.getA()[source]

返回一个数组对象

Return self as an ndarray object.

Equivalent to np.asarray(self).

Parameters: None
Returns: ret : ndarray
self as an ndarray

Examples

>>> x = np.matrix(np.arange(12).reshape((3,4))); x
matrix([[ 0,  1,  2,  3],
        [ 4,  5,  6,  7],
        [ 8,  9, 10, 11]])
>>> x.getA()
array([[ 0,  1,  2,  3],
       [ 4,  5,  6,  7],
       [ 8,  9, 10, 11]])

numpy.matrix.transpose

矩阵转置

Returns a view of the array with axes transposed.

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.) For a 2-D array, this is the usual matrix transpose. For an n-D array, if axes are given, their order indicates how the axes are permuted (see Examples). If axes are not provided and a.shape = (i[0], i[1], … i[n-2], i[n-1]), then a.transpose().shape = (i[n-1], i[n-2], … i[1], i[0]).
、

Examples

>>> a = np.array([[1, 2], [3, 4]])
>>> a
array([[1, 2],
       [3, 4]])
>>> a.transpose()
array([[1, 3],
       [2, 4]])
>>> a.transpose((1, 0))
array([[1, 3],
       [2, 4]])
>>> a.transpose(1, 0)
array([[1, 3],
       [2, 4]])