实操笔记03-数据切片[:,None]

[:,None]
None表示该维不进行切片，而是将该维整体作为数组元素处理。
所以，[:,None]的效果就是将二维数组按每行分割，最后形成一个三维数组

features.head()

temp = np.array(features)
print(temp[:,None])

[[[ 0. 0. -1.33460919 ..., 0. 0. 1. ]]

[[ 0. 0. -1.43847501 ..., 0. 0. 1. ]]

[[ 0. 0. -1.43847501 ..., 0. 0. 1. ]]

...,
[[ 1. 0. 0.11951233 ..., 0. 0. 0. ]]

[[ 1. 0. -0.19208513 ..., 0. 0. 0. ]]

[[ 1. 0. -0.19208513 ..., 0. 0. 0. ]]]

temp1 = temp[:,None]
print(temp1.shape)
print(temp1.ndim)

(16875, 1, 56)
3