numpy.format_parser()

class numpy.format_parser(formats, names, titles, aligned=False, byteorder=None) [source]

Class to convert formats, names, titles description to a dtype.

After constructing the format_parser object, the dtype attribute is the converted data-type: dtype = format_parser(formats, names, titles).dtype

Parameters:

Parameters:	formats : str or list of str The format description, either specified as a string with comma-separated format descriptions in the form `'f8, i4, a5'`, or a list of format description strings in the form `['f8', 'i4', 'a5']`. names : str or list/tuple of str The field names, either specified as a comma-separated string in the form `'col1, col2, col3'`, or as a list or tuple of strings in the form `['col1', 'col2', 'col3']`. An empty list can be used, in that case default field names (?f0?, ?f1?, ...) are used. titles : sequence Sequence of title strings. An empty list can be used to leave titles out. aligned : bool, optional If True, align the fields by padding as the C-compiler would. Default is False. byteorder : str, optional If specified, all the fields will be changed to the provided byte-order. Otherwise, the default byte-order is used. For all available string specifiers, see `dtype.newbyteorder`.

formats : str or list of str

The format description, either specified as a string with comma-separated format descriptions in the form 'f8, i4, a5', or a list of format description strings in the form ['f8', 'i4', 'a5'].

names : str or list/tuple of str

The field names, either specified as a comma-separated string in the form 'col1, col2, col3', or as a list or tuple of strings in the form ['col1', 'col2', 'col3']. An empty list can be used, in that case default field names (?f0?, ?f1?, ...) are used.

titles : sequence

Sequence of title strings. An empty list can be used to leave titles out.

aligned : bool, optional

If True, align the fields by padding as the C-compiler would. Default is False.

byteorder : str, optional

If specified, all the fields will be changed to the provided byte-order. Otherwise, the default byte-order is used. For all available string specifiers, see dtype.newbyteorder.

Examples

>>> np.format_parser(['f8', 'i4', 'a5'], ['col1', 'col2', 'col3'],
...                  ['T1', 'T2', 'T3']).dtype
dtype([(('T1', 'col1'), '<f8'), (('T2', 'col2'), '<i4'),
       (('T3', 'col3'), '|S5')])

names and/or titles can be empty lists. If titles is an empty list, titles will simply not appear. If names is empty, default field names will be used.

>>> np.format_parser(['f8', 'i4', 'a5'], ['col1', 'col2', 'col3'],
...                  []).dtype
dtype([('col1', '<f8'), ('col2', '<i4'), ('col3', '|S5')])
>>> np.format_parser(['f8', 'i4', 'a5'], [], []).dtype
dtype([('f0', '<f8'), ('f1', '<i4'), ('f2', '|S5')])

Attributes

dtype

(dtype) The converted data-type.

Links:

https://docs.scipy.org/doc/numpy-1.11.0/reference/generated/numpy.format_parser.html

doc_NumPy

2025-01-10 15:47:30

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