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chararray(shape, itemsize=1, unicode=False, buffer=None, offset=0, strides=None, order=None)

note

The :None:None:`chararray` class exists for backwards compatibility with Numarray, it is not recommended for new development. Starting from numpy 1.4, if one needs arrays of strings, it is recommended to use arrays of :None:None:`dtype` :None:None:`object_`, :None:None:`string_` or :None:None:`unicode_`, and use the free functions in the :None:None:`numpy.char` module for fast vectorized string operations.

Versus a regular NumPy array of type :None:None:`str` or :None:None:`unicode`, this class adds the following functionality:

values automatically have whitespace removed from the end when indexed

comparison operators automatically remove whitespace from the end when comparing values

vectorized string operations are provided as methods (e.g. :None:None:`.endswith`) and infix operators (e.g. "+", "*", "%" )

chararrays should be created using numpy.char.array or numpy.char.asarray , rather than this constructor directly.

This constructor creates the array, using :None:None:`buffer` (with :None:None:`offset` and :None:None:`strides`) if it is not None . If :None:None:`buffer` is None , then constructs a new array with :None:None:`strides` in "C order", unless both len(shape) >= 2 and order='F' , in which case :None:None:`strides` is in "Fortran order".

Methods

Parameters

shape : tuple: Shape of the array.
itemsize : int, optional: Length of each array element, in number of characters. Default is 1.
unicode : bool, optional: Are the array elements of type unicode (True) or string (False). Default is False.
buffer : object exposing the buffer interface or str, optional: Memory address of the start of the array data. Default is None, in which case a new array is created.
offset : int, optional: Fixed stride displacement from the beginning of an axis? Default is 0. Needs to be >=0.
strides : array_like of ints, optional: Strides for the array (see :None:None:`ndarray.strides` for full description). Default is None.
order : {'C', 'F'}, optional: The order in which the array data is stored in memory: 'C' -> "row major" order (the default), 'F' -> "column major" (Fortran) order.

Provides a convenient view on arrays of string and unicode values.

Examples

>>> charar = np.chararray((3, 3))
... charar[:] = 'a'
... charar
chararray([[b'a', b'a', b'a'],
           [b'a', b'a', b'a'],
           [b'a', b'a', b'a']], dtype='|S1')

>>> charar = np.chararray(charar.shape, itemsize=5)
... charar[:] = 'abc'
... charar
chararray([[b'abc', b'abc', b'abc'],
           [b'abc', b'abc', b'abc'],
           [b'abc', b'abc', b'abc']], dtype='|S5')

See :

Back References

The following pages refer to to this document either explicitly or contain code examples using this.

numpy.char.array numpy.char.asarray

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