Numpy文件操作

Numpy可以以文本或二进制模式存储和读取数组数据。

np.save(file,array) ： 以二进制文件存储数组数据，文件后缀为.npy，可自动添加后缀。

np.savez(file, *args, **kwds)：以二进制文件不压缩存储多个数组数据到一个文件中，文件后缀为.npz。

np.savez_compressed(file, *args, **kwds)：以二进制文件压缩存储多个数组数据到一个文件中，文件后缀为.npz。

np.load(file)：从pickle 、.npy 、.npz 类型文件读取数组数据。

In [1]: import numpy as np

In [2]: arr = np.arange(10)
In [3]: arr
Out[3]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

#np.save(file,array) : Save an array to a binary file in NumPy ``.npy`` format.
In [4]: np.save('some_array',arr)
    
#np.load(file)：Load arrays or pickled objects from ``.npy``, ``.npz`` or pickled files.   
In [6]: arr1 = np.load('some_array.npy')

In [7]: arr1
Out[7]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
    
In [8]: arr2 = np.arange(10).reshape(5,2)
In [9]: arr2
Out[9]:
array([[0, 1],
       [2, 3],
       [4, 5],
       [6, 7],
       [8, 9]])

#np.savez(file, *args, **kwds):Save several arrays into a single file in uncompressed ``.npz`` format.
In [14]: np.savez('array_archive2.npz',a = arr1,b=arr2)

In [15]: arch2 = np.load('array_archive2.npz')

In [17]: arch2['a']
Out[17]:
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

In [18]: arch2['b']
Out[18]:
array([[0, 1],
       [2, 3],
       [4, 5],
       [6, 7],
       [8, 9]])

#np.savez_compressed(file, *args, **kwds):Save several arrays into a single file in compressed ``.npz`` format.
In [19]: np.savez_compressed('array_compressed.npz',a = arr,b=arr2)
In [20]: arch3['a']
Out[20]:
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

In [21]: arch3['b']
Out[21]:
array([[0, 1],
       [2, 3],
       [4, 5],
       [6, 7],
       [8, 9]])