numpy.binary_repr#
- 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 [1]. A N-bit two’s-complement system can represent every integer in the range \(-2^{N-1}\) to \(+2^{N-1}-1\).
- Parameters
- numint
Only an integer decimal number can be used.
- widthint, optional
The length of the returned string if num is positive, or the length of the two’s complement if num is negative, provided that width is at least a sufficient number of bits for num to be represented in the designated form.
If the width value is insufficient, it will be ignored, and num will be returned in binary (num > 0) or two’s complement (num < 0) form with its width equal to the minimum number of bits needed to represent the number in the designated form. This behavior is deprecated and will later raise an error.
Deprecated since version 1.12.0.
- Returns
- binstr
Binary representation of num or two’s complement of num.
See also
Notes
binary_repr
is equivalent to usingbase_repr
with base 2, but about 25x faster.References
- 1
Wikipedia, “Two’s complement”, https://en.wikipedia.org/wiki/Two’s_complement
Examples
>>> np.binary_repr(3) '11' >>> np.binary_repr(-3) '-11' >>> np.binary_repr(3, width=4) '0011'
The two’s complement is returned when the input number is negative and width is specified:
>>> np.binary_repr(-3, width=3) '101' >>> np.binary_repr(-3, width=5) '11101'