17.NumPy之数组合并和拆分（本章尚有疑惑，待日后实际应用再加以理解）

#NumPy之 数组合并和拆分
import numpy as np


#对数组进行变形
a = np.arange(20).reshape((5, 4))
print('(5,4):')
print(a)
a = np.arange(20).reshape((5, -1))
print('(5,-1):')
print(a)

a = np.floor(10 * np.random.random((2, 2, 2)))
print('array a:')
print(a)
b = np.floor(10 * np.random.random((2, 2, 2)))
print('array b:')
print(b)

c = np.vstack((a, b))
print('array c:')
print(c)

#合并数组
a=np.arange(12)
b=np.arange(12)

#沿着一个新的维度（dimension、axis）合并数组，得到一个的数组维度加一
print('stack array:')
print(np.stack((a,b)))
# output:
# [[ 0  1  2  3  4  5  6  7  8  9 10 11]
#  [ 0  1  2  3  4  5  6  7  8  9 10 11]]
print(np.stack((a,b),axis=-1))
# output:
# [[ 0  0]
#  [ 1  1]
#  [ 2  2]
#  [ 3  3]
#  [ 4  4]
#  [ 5  5]
#  [ 6  6]
#  [ 7  7]
#  [ 8  8]
#  [ 9  9]
#  [10 10]
#  [11 11]]
print(np.stack((a,b),axis=1))
# output:
# [[ 0  0]
#  [ 1  1]
#  [ 2  2]
#  [ 3  3]
#  [ 4  4]
#  [ 5  5]
#  [ 6  6]
#  [ 7  7]
#  [ 8  8]
#  [ 9  9]
#  [10 10]
#  [11 11]]