numpy.asarray — NumPy v2.5.dev0 Manual (original) (raw)

numpy.asarray(a, dtype=None, order=None, *, device=None, copy=None, like=None)#

Convert the input to an array.

Parameters:

aarray_like

Input data, in any form that can be converted to an array. This includes lists, lists of tuples, tuples, tuples of tuples, tuples of lists and ndarrays.

dtypedata-type, optional

By default, the data-type is inferred from the input data.

order{‘C’, ‘F’, ‘A’, ‘K’}, optional

The memory layout of the output. ‘C’ gives a row-major layout (C-style), ‘F’ gives a column-major layout (Fortran-style). ‘C’ and ‘F’ will copy if needed to ensure the output format. ‘A’ (any) is equivalent to ‘F’ if input a is non-contiguous or Fortran-contiguous, otherwise, it is equivalent to ‘C’. Unlike ‘C’ or ‘F’, ‘A’ does not ensure that the result is contiguous. ‘K’ (keep) is the default and preserves the input order for the output.

devicestr, optional

The device on which to place the created array. Default: None. For Array-API interoperability only, so must be "cpu" if passed.

New in version 2.0.0.

copybool, optional

If True, then the object is copied. If None then the object is copied only if needed, i.e. if __array__ returns a copy, if obj is a nested sequence, or if a copy is needed to satisfy any of the other requirements (dtype, order, etc.). For False it raises a ValueError if a copy cannot be avoided. Default: None.

New in version 2.0.0.

likearray_like, optional

Reference object to allow the creation of arrays which are not NumPy arrays. If an array-like passed in as like supports the __array_function__ protocol, the result will be defined by it. In this case, it ensures the creation of an array object compatible with that passed in via this argument.

New in version 1.20.0.

Returns:

outndarray

Array interpretation of a. No copy is performed if the input is already an ndarray with matching dtype and order. If a is a subclass of ndarray, a base class ndarray is returned.

Examples

Convert a list into an array:

a = [1, 2] import numpy as np np.asarray(a) array([1, 2])

Existing arrays are not copied:

a = np.array([1, 2]) np.asarray(a) is a True

If dtype is set, array is copied only if dtype does not match:

a = np.array([1, 2], dtype=np.float32) np.shares_memory(np.asarray(a, dtype=np.float32), a) True np.shares_memory(np.asarray(a, dtype=np.float64), a) False

Contrary to asanyarray, ndarray subclasses are not passed through:

issubclass(np.recarray, np.ndarray) True a = np.array([(1., 2), (3., 4)], dtype='f4,i4').view(np.recarray) np.asarray(a) is a False np.asanyarray(a) is a True