Convert to binary and keep leading zeros in Python
Use the format()
function:
>>> format(14, '#010b')
'0b00001110'
The format()
function simply formats the input following the Format Specification mini language. The #
makes the format include the 0b
prefix, and the 010
size formats the output to fit in 10 characters width, with 0
padding; 2 characters for the 0b
prefix, the other 8 for the binary digits.
This is the most compact and direct option.
If you are putting the result in a larger string, use an formatted string literal (3.6+) or use str.format()
and put the second argument for the format()
function after the colon of the placeholder {:..}
:
>>> value = 14
>>> f'The produced output, in binary, is: {value:#010b}'
'The produced output, in binary, is: 0b00001110'
>>> 'The produced output, in binary, is: {:#010b}'.format(value)
'The produced output, in binary, is: 0b00001110'
As it happens, even for just formatting a single value (so without putting the result in a larger string), using a formatted string literal is faster than using format()
:
>>> import timeit
>>> timeit.timeit("f_(v, '#010b')", "v = 14; f_ = format") # use a local for performance
0.40298633499332936
>>> timeit.timeit("f'{v:#010b}'", "v = 14")
0.2850222919951193
But I'd use that only if performance in a tight loop matters, as format(...)
communicates the intent better.
If you did not want the 0b
prefix, simply drop the #
and adjust the length of the field:
>>> format(14, '08b')
'00001110'
>>> '{:08b}'.format(1)
'00000001'
See: Format Specification Mini-Language
Note for Python 2.6 or older, you cannot omit the positional argument identifier before :
, so use
>>> '{0:08b}'.format(1)
'00000001'
I am using
bin(1)[2:].zfill(8)
will print
'00000001'