numpy.sign

numpy.sign(x[, out]) = <ufunc 'sign'>

Returns an element-wise indication of the sign of a number.

The sign function returns -1 if x < 0, 0 if x==0, 1 if x > 0. nan is returned for nan inputs.

For complex inputs, the sign function returns sign(x.real) + 0j if x.real != 0 else sign(x.imag) + 0j.

complex(nan, 0) is returned for complex nan inputs.

Parameters:

x : array_like

Input values.

Returns:

y : ndarray

The sign of x.

Notes

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, .

Examples

>>> np.sign([-5., 4.5])
array([-1.,  1.])
>>> np.sign(0)
0
>>> np.sign(5-2j)
(1+0j)