Numpy Notebook

导入numpy

import numpy as np

数据类型转换(astype)

a = np.array([[1,2,3],[4,5,6]])
print(a.dtype)
a.astype('float32')

多维数组降维

# a.shape = (1, 9)
a = np.ones((1,9))

# b.shape = (9, )
b = a[0, :]

多维数组增维

# b.shape = (9, )
b = np.ones(9)
# c.shape = (1, 9)
c = b[None, :]
# d.shape = (9, 1)
d = b[:, None]