True/False formats as 1/0 in a fixed width string

Frank Millman frank at chagford.com
Wed Mar 27 10:22:16 CET 2013


On 27/03/2013 10:55, Dave Angel wrote:
> On 03/27/2013 04:40 AM, Frank Millman wrote:
>> Hi all
>>
>> This is a bit of trivia, really, as I don't need a solution.
>>
>> But someone might need it one day, so it is worth mentioning.
>>
>>  >>> '{}'.format(True)
>> 'True'
>>  >>> '{:<10}'.format(True)
>> '1         '
>>
>> One might want to format True/False in a fixed width string, but it
>> returns 1/0 instead. Is there any way to make this work?
>>
>> Frank Millman
>>
>
> Easiest way is to surround the boolean variable with repr()
>
> flag = True
> '{:<10}'.format(repr(flag))
>
> An alternative is to just use something like:
>
> ["False     ","True      "][flag]
>
> making sure the two strings are of the same length.
>
> (You didn't specify version, but I tested these with CPython 2.7.3)
>

Thanks, Dave. I am using CPython 3.3.0, which behaves the same for this 
purpose.

Your solutions work, but in my case I am reading in data from a 
database, so I want to create a format string, and then just call

     print(format_string.format(*row))

so I can't easily modify the contents of a single column.

Peter's solution works perfectly for this scenario -

 >>> '{!s:<10}'.format(True)
'True      '

I had to look up what '!s' means. From the manual -

"Three conversion flags are currently supported: '!s' which calls str() 
on the value, '!r' which calls repr() and '!a' which calls ascii()."

Another obscure but useful tip to store away somewhere.

Frank





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