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- ''' Byteorder utilities for system - numpy byteorder encoding
- Converts a variety of string codes for little endian, big endian,
- native byte order and swapped byte order to explicit NumPy endian
- codes - one of '<' (little endian) or '>' (big endian)
- '''
- import sys
- __all__ = [
- 'aliases', 'native_code', 'swapped_code',
- 'sys_is_le', 'to_numpy_code'
- ]
- sys_is_le = sys.byteorder == 'little'
- native_code = sys_is_le and '<' or '>'
- swapped_code = sys_is_le and '>' or '<'
- aliases = {'little': ('little', '<', 'l', 'le'),
- 'big': ('big', '>', 'b', 'be'),
- 'native': ('native', '='),
- 'swapped': ('swapped', 'S')}
- def to_numpy_code(code):
- """
- Convert various order codings to NumPy format.
- Parameters
- ----------
- code : str
- The code to convert. It is converted to lower case before parsing.
- Legal values are:
- 'little', 'big', 'l', 'b', 'le', 'be', '<', '>', 'native', '=',
- 'swapped', 's'.
- Returns
- -------
- out_code : {'<', '>'}
- Here '<' is the numpy dtype code for little endian,
- and '>' is the code for big endian.
- Examples
- --------
- >>> import sys
- >>> sys_is_le == (sys.byteorder == 'little')
- True
- >>> to_numpy_code('big')
- '>'
- >>> to_numpy_code('little')
- '<'
- >>> nc = to_numpy_code('native')
- >>> nc == '<' if sys_is_le else nc == '>'
- True
- >>> sc = to_numpy_code('swapped')
- >>> sc == '>' if sys_is_le else sc == '<'
- True
- """
- code = code.lower()
- if code is None:
- return native_code
- if code in aliases['little']:
- return '<'
- elif code in aliases['big']:
- return '>'
- elif code in aliases['native']:
- return native_code
- elif code in aliases['swapped']:
- return swapped_code
- else:
- raise ValueError(
- 'We cannot handle byte order %s' % code)
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