np.column_stack()數組與列表list的區別

關於np.column_stack()裏面1維數組使用[1維數據]之後的區別

import numpy as np
# np.array((1,2,3),(11,22,33))
a=[1,2,3];b=[11,22,33];np.column_stack((a,b))
a=[[1,2,3],[10,20,30]];b=[[11,22,33],[110,220,330]];np.column_stack((a,b))

array([[  1,   2,   3,  11,  22,  33],
       [ 10,  20,  30, 110, 220, 330]])

ab = np.column_stack([np.array(a),np.array(b)])
print(ab,ab.shape)
ab.mean(axis=1)

[[  1   2   3  11  22  33]
 [ 10  20  30 110 220 330]] (2, 6)





array([  12.,  120.])

ab = np.column_stack([np.array(a)])
print(ab,ab.shape)
ab.mean(axis=1)

[[ 1  2  3]
 [10 20 30]] (2, 3)





array([  2.,  20.])

a=[1,2,3];b=[11,22,33];
np.column_stack((a,b)).mean(axis=1)

array([  6.,  12.,  18.])

[np.column_stack([i]*4)  for i in list(range(1,4))]

[array([[1, 1, 1, 1]]), array([[2, 2, 2, 2]]), array([[3, 3, 3, 3]])]

[np.column_stack([i]*4).mean(axis=1)  for i in list(range(1,4))]

[array([ 1.]), array([ 2.]), array([ 3.])]