sign(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj]) = <ufunc 'sign'>¶
Returns an element-wise indication of the sign of a number.
-1 if x < 0, 0 if x==0, 1 if x > 0. nan is returned for nan inputs.
For complex inputs, the
sign(x.real) + 0j if x.real != 0 else sign(x.imag) + 0j.
complex(nan, 0) is returned for complex nan inputs.
- outndarray, None, or tuple of ndarray and None, optional
A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated array is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.
- wherearray_like, optional
This condition is broadcast over the input. At locations where the condition is True, the out array will be set to the ufunc result. Elsewhere, the out array will retain its original value. Note that if an uninitialized out array is created via the default
out=None, locations within it where the condition is False will remain uninitialized.
For other keyword-only arguments, see the ufunc docs.
The sign of x. This is a scalar if x is a scalar.
There is more than one definition of sign in common use for complex numbers. The definition used here is equivalent to which is different from a common alternative, .
>>> np.sign([-5., 4.5]) array([-1., 1.]) >>> np.sign(0) 0 >>> np.sign(5-2j) (1+0j)