numpy.can_cast¶
-
numpy.
can_cast
(from_, to, casting='safe')¶ Returns True if cast between data types can occur according to the casting rule. If from is a scalar or array scalar, also returns True if the scalar value can be cast without overflow or truncation to an integer.
Parameters: from_ : dtype, dtype specifier, scalar, or array
Data type, scalar, or array to cast from.
to : dtype or dtype specifier
Data type to cast to.
casting : {‘no’, ‘equiv’, ‘safe’, ‘same_kind’, ‘unsafe’}, optional
Controls what kind of data casting may occur.
- ‘no’ means the data types should not be cast at all.
- ‘equiv’ means only byte-order changes are allowed.
- ‘safe’ means only casts which can preserve values are allowed.
- ‘same_kind’ means only safe casts or casts within a kind, like float64 to float32, are allowed.
- ‘unsafe’ means any data conversions may be done.
Returns: out : bool
True if cast can occur according to the casting rule.
See also
Notes
Starting in NumPy 1.9, can_cast function now returns False in ‘safe’ casting mode for integer/float dtype and string dtype if the string dtype length is not long enough to store the max integer/float value converted to a string. Previously can_cast in ‘safe’ mode returned True for integer/float dtype and a string dtype of any length.
Examples
Basic examples
>>> np.can_cast(np.int32, np.int64) True >>> np.can_cast(np.float64, complex) True >>> np.can_cast(complex, float) False
>>> np.can_cast('i8', 'f8') True >>> np.can_cast('i8', 'f4') False >>> np.can_cast('i4', 'S4') False
Casting scalars
>>> np.can_cast(100, 'i1') True >>> np.can_cast(150, 'i1') False >>> np.can_cast(150, 'u1') True
>>> np.can_cast(3.5e100, np.float32) False >>> np.can_cast(1000.0, np.float32) True
Array scalar checks the value, array does not
>>> np.can_cast(np.array(1000.0), np.float32) True >>> np.can_cast(np.array([1000.0]), np.float32) False
Using the casting rules
>>> np.can_cast('i8', 'i8', 'no') True >>> np.can_cast('<i8', '>i8', 'no') False
>>> np.can_cast('<i8', '>i8', 'equiv') True >>> np.can_cast('<i4', '>i8', 'equiv') False
>>> np.can_cast('<i4', '>i8', 'safe') True >>> np.can_cast('<i8', '>i4', 'safe') False
>>> np.can_cast('<i8', '>i4', 'same_kind') True >>> np.can_cast('<i8', '>u4', 'same_kind') False
>>> np.can_cast('<i8', '>u4', 'unsafe') True