sign

sign(x, out=None, **kwargs)

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. Only supports real number.

Parameters:

x : ndarray or a scalar

Input values.

out : ndarray or None, optional

A location into which the result is stored. If provided, it must have the same shape and dtype as input ndarray. If not provided or None, a freshly-allocated array is returned.

Returns:

y : ndarray

The sign of x. This is a scalar if x is a scalar.

Examples

>>> a = np.array([-5., 4.5])
>>> np.sign(a)
array([-1.,  1.])
Scalars as input:
>>> np.sign(4.0)
1.0
>>> np.sign(0)
0
Use ``out`` parameter:
>>> b = np.zeros((2, ))
>>> np.sign(a, out=b)
array([-1.,  1.])
>>> b
array([-1.,  1.])