pytorch的tensor與numpy數組轉換

看代碼，tensor轉numpy:
a = torch.ones(2,2)
b = a.numpy()
print(type(a))
print(type(b))
print(a)
print(b)
輸出爲：
<class ‘torch.Tensor’>
<class ‘numpy.ndarray’>
tensor([[1., 1.],
[1., 1.]])
[[1. 1.]
[1. 1.]]

numpy轉tensor：
import torch
import numpy as np

a = np.ones(5)
b = torch.from_numpy(a)
print(type(a))
print(type(b))
print(a)
print(b)
輸出爲：
<class ‘numpy.ndarray’>
<class ‘torch.Tensor’>
[1. 1. 1. 1. 1.]
tensor([1., 1., 1., 1., 1.], dtype=torch.float64)
可見pytorch的tensor對象與numpy數組是可以相互轉換的，且numpy數組的默認類型是double