import numpy as np
tang_arrary=np.arange(10)
tang_arrary

array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

tang_arrary.shape#形状

(10,)

tang_arrary.shape=2,5#指定2行5列

tang_arrary

array([[0, 1, 2, 3, 4],
       [5, 6, 7, 8, 9]])

tang_arrary.reshape(1,10)#改形状的方法2

array([[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]])

大小必须不能改变

tang_arrary.shape=3,4

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-6-236d4f50caba> in <module>()
----> 1tang_arrary.shape=3,4

ValueError: cannot reshape array of size 10 into shape (3,4)

tang_arrary=np.arange(10)
tang_arrary.shape

(10,)

tang_arrary=tang_arrary[np.newaxis,:]#新加一个维度
tang_arrary.shape

(1, 10)

tang_arrary=tang_arrary[:,np.newaxis]#新加一个维度
tang_arrary.shape

(1, 1, 10)

tang_arrary=tang_arrary[:,np.newaxis,np.newaxis]#新加2个维度
tang_arrary.shape

(1, 1, 1, 1, 10)

tang_arrary=tang_arrary.squeeze()#压缩,空轴会被去掉
tang_arrary.shape

(10,)

tang_arrary.shape=2,5

tang_arrary

array([[0, 1, 2, 3, 4],
       [5, 6, 7, 8, 9]])

转置：不改变原来的变量

tang_arrary.T

array([[0, 5],
       [1, 6],
       [2, 7],
       [3, 8],
       [4, 9]])

tang_arrary.transpose()

array([[0, 5],
       [1, 6],
       [2, 7],
       [3, 8],
       [4, 9]])

数组的连接

a=np.array([[123,456,678],[321,344,451]])
a

array([[123, 456, 678],
       [321, 344, 451]])

b=np.array([[133,444,412],[234,742,453]])
b

array([[133, 444, 412],
       [234, 742, 453]])

拼接

c=np.concatenate((a,b))#第二个括号必须是元组形式
c

array([[123, 456, 678],
       [321, 344, 451],
       [133, 444, 412],
       [234, 742, 453]])

c=np.concatenate((a,b),axis=0)#按照列拼接
c

array([[123, 456, 678],
       [321, 344, 451],
       [133, 444, 412],
       [234, 742, 453]])

c=np.concatenate((a,b),axis=1)#按照行拼接
c

array([[123, 456, 678, 133, 444, 412],
       [321, 344, 451, 234, 742, 453]])

c.shape

(2, 6)

np.vstack((a,b))#默认轴=0

array([[123, 456, 678],
       [321, 344, 451],
       [133, 444, 412],
       [234, 742, 453]])

np.hstack((a,b))#默认轴=1

array([[123, 456, 678, 133, 444, 412],
       [321, 344, 451, 234, 742, 453]])

a.flatten()#把数值拉平，不改变原始数组

array([123, 456, 678, 321, 344, 451])

a

array([[123, 456, 678],
       [321, 344, 451]])

a.ravel()#把数值拉平，不改变原始数组

array([123, 456, 678, 321, 344, 451])