numpy.binary_repr(num, width=None)[source]

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

For negative numbers, if width is not given, a minus sign is added to the front. If width is given, the two’s complement of the number is returned, with respect to that width.

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 [R16]. A N-bit two’s-complement system can represent every integer in the range -2^{N-1} to +2^{N-1}-1.

Parameters :

num : int

Only an integer decimal number can be used.

width : int, optional

The length of the returned string if num is positive, the length of the two’s complement if num is negative.

Returns :

bin : str

Binary representation of num or two’s complement of num.

See also

Return a string representation of a number in the given base system.


binary_repr is equivalent to using base_repr with base 2, but about 25x faster.


[R16](1, 2) Wikipedia, “Two’s complement”,’s_complement


>>> np.binary_repr(3)
>>> np.binary_repr(-3)
>>> np.binary_repr(3, width=4)

The two’s complement is returned when the input number is negative and width is specified:

>>> np.binary_repr(-3, width=4)

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