Reputation: 914
I am trying to store matrices into an array, however when I append the matrix, it would get every element and output just an 1 dimensional array.
Example Code:
matrix_array= np.array([])
for y in y_label:
matrix_array= np.append(matrix_array, np.identity(3))
Upvotes: 0
Views: 182
Reputation: 231665
Clearly np.append
is the wrong tool for the job:
In [144]: np.append(np.array([]), np.identity(3))
Out[144]: array([ 1., 0., 0., 0., 1., 0., 0., 0., 1.])
From its docs:
If
axis
is not specified,values
can be any shape and will be flattened before use.
With list append
In [153]: alist=[]
In [154]: for y in [1,2]:
...: alist.append(np.identity(3))
...:
In [155]: alist
Out[155]:
[array([[ 1., 0., 0.],
[ 0., 1., 0.],
[ 0., 0., 1.]]), array([[ 1., 0., 0.],
[ 0., 1., 0.],
[ 0., 0., 1.]])]
In [156]: np.array(alist)
Out[156]:
array([[[ 1., 0., 0.],
[ 0., 1., 0.],
[ 0., 0., 1.]],
[[ 1., 0., 0.],
[ 0., 1., 0.],
[ 0., 0., 1.]]])
In [157]: _.shape
Out[157]: (2, 3, 3)
Upvotes: 1