/NumPy 1.17


numpy.invert(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj]) = <ufunc 'invert'>

Compute bit-wise inversion, or bit-wise NOT, element-wise.

Computes the bit-wise NOT of the underlying binary representation of the integers in the input arrays. This ufunc implements the C/Python operator ~.

For signed integer inputs, the two’s complement is returned. In a two’s-complement system negative numbers are represented by the two’s complement of the absolute value. This is the most common method of representing signed integers on computers [1]. A N-bit two’s-complement system can represent every integer in the range -2^{N-1} to +2^{N-1}-1.

x : array_like

Only integer and boolean types are handled.

out : ndarray, 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.

where : array_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.

out : ndarray or scalar

Result. This is a scalar if x is a scalar.

See also

bitwise_and, bitwise_or, bitwise_xor, logical_not

Return the binary representation of the input number as a string.


bitwise_not is an alias for invert:

>>> np.bitwise_not is np.invert


[1] Wikipedia, “Two’s complement”, https://en.wikipedia.org/wiki/Two’s_complement


We’ve seen that 13 is represented by 00001101. The invert or bit-wise NOT of 13 is then:

>>> x = np.invert(np.array(13, dtype=np.uint8))
>>> x
>>> np.binary_repr(x, width=8)

The result depends on the bit-width:

>>> x = np.invert(np.array(13, dtype=np.uint16))
>>> x
>>> np.binary_repr(x, width=16)

When using signed integer types the result is the two’s complement of the result for the unsigned type:

>>> np.invert(np.array([13], dtype=np.int8))
array([-14], dtype=int8)
>>> np.binary_repr(-14, width=8)

Booleans are accepted as well:

>>> np.invert(np.array([True, False]))
array([False,  True])

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