astype

astype(x: array, dtype: dtype, /, *, copy: bool = True) → array

Copies an array to a specified data type irrespective of Type Promotion Rules rules.

Note

Casting floating-point NaN and infinity values to integral data types is not specified and is implementation-dependent.

Note

Casting a complex floating-point array to a real-valued data type should not be permitted.

Historically, when casting a complex floating-point array to a real-valued data type, libraries such as NumPy have discarded imaginary components such that, for a complex floating-point array x, astype(x) equals astype(real(x))). This behavior is considered problematic as the choice to discard the imaginary component is arbitrary and introduces more than one way to achieve the same outcome (i.e., for a complex floating-point array x, astype(x) and astype(real(x)) versus only astype(imag(x))). Instead, in order to avoid ambiguity and to promote clarity, this specification requires that array API consumers explicitly express which component should be cast to a specified real-valued data type.

Note

When casting a boolean input array to a real-valued data type, a value of True must cast to a real-valued number equal to 1, and a value of False must cast to a real-valued number equal to 0.

When casting a boolean input array to a complex floating-point data type, a value of True must cast to a complex number equal to 1 + 0j, and a value of False must cast to a complex number equal to 0 + 0j.

Note

When casting a real-valued input array to bool, a value of 0 must cast to False, and a non-zero value must cast to True.

When casting a complex floating-point array to bool, a value of 0 + 0j must cast to False, and all other values must cast to True.

Parameters:

  • x (array) – array to cast.

  • dtype (dtype) – desired data type.

  • copy (bool) – specifies whether to copy an array when the specified dtype matches the data type of the input array x. If True, a newly allocated array must always be returned. If False and the specified dtype matches the data type of the input array, the input array must be returned; otherwise, a newly allocated array must be returned. Default: True.

Returns:

out (array) – an array having the specified data type. The returned array must have the same shape as x.

Notes

Changed in version 2022.12: Added complex data type support.