将numpy数组保存到二进制fi

Question

我以np.save("image_mean.npy", averaged_mean)的形式将numpy数组保存到一个二进制文件中。当我打开文件时，观察到bianry文件的头是“NUMPY V {'descr': '<f8', 'fortran_order': False, 'shape': (3L, 704L, 1248L), }。在

我的问题是NUMPY V指的是什么？ 如果我希望它是NUMPY F“NUMPY F {'descr': '<f8', 'fortran_order': False, 'shape': (3L, 704L, 1248L), }，那么在np.saveAPI中如何更改？在

Answer 1

V是头数据的长度（包括空格填充和终止换行）。在

如the documentation -

1. The first 6 bytes are a magic string: exactly “x93NUMPY”.

2. The next 1 byte is an unsigned byte: the major version number of the file format, e.g. x01.

3. The next 1 byte is an unsigned byte: the minor version number of the file format, e.g. x00. Note: the version of the file format is not tied to the version of the numpy package.

4. The next 2 bytes form a little-endian unsigned short int: the length of the header data HEADER_LEN.

5. The next HEADER_LEN bytes form the header data describing the array’s format. It is an ASCII string which contains a Python literal expression of a dictionary. It is terminated by a newline (‘n’) and padded with spaces (‘x20’) to make the total length of the magic string + 4 + HEADER_LEN be evenly divisible by 16 for alignment purposes.

示例中的头数据（包括一个换行符）的长度为71。这使得magic_string + 4 + HEADER_LEN等于81，它不能被16整除，所以下一个可整除的数字是96，因此头数据被15个空格填充，这样总长度就等于96。这使得头的长度为-86。它是V。在

>>> chr(86)
'V'