How to control length of the result of string.format(bool_value) in Python?

Question

What the equivalent way to str.format function for converting booleans into strings?

>>> "%5s" % True
' True'

>>> "%5s" % False
'False'

Please note the space in ' True'. This always makes the length the same for 'True' and 'False'.

I've check the methods in this post:

How are booleans formatted in Strings in Python?

None of them can do the same thing.

Michael come lately · Accepted Answer · 2022-03-18 14:03:09Z

You can use type conversion flags to do what you wanted:

'{:_>5}'.format(True)   # Oh no! it's '____1'
'{!s:_>5}'.format(True) # Now we get  '_True'

Note the !s. I used an underscore to show the padding more clearly. It also works with f-strings:

f'{True:_>5}'   # '____1'
f'{True!s:_>5}' # '_True'

Relevant documentation:

6.1.3. Format String Syntax

[...]

The conversion field causes a type coercion before formatting. Normally, the job of formatting a value is done by the __format__() method of the value itself. However, in some cases it is desirable to force a type to be formatted as a string, overriding its own definition of formatting. By converting the value to a string before calling __format__(), the normal formatting logic is bypassed.

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

Some examples:
"Harold's a clever {0!s}"        # Calls str() on the argument first
"Bring out the holy {name!r}"    # Calls repr() on the argument first
"More {!a}"                      # Calls ascii() on the argument first

jan · Accepted Answer · 2016-04-12 13:05:15Z

1

You can use the str() function. More about it here.

Here are some examples:

x = str(True)
y = False

print( type(x) )
<class 'str'>   # This is a string

print( type(y) )
<class 'bool'>  # This is a boolean

answered Apr 12, 2016 at 13:05

jan

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Syrtis Major · Accepted Answer · 2016-04-12 13:17:03Z

1

I found that "{:>5}".format(str(True)) works fine. The output is exactly the same as "%5s" % True, ie ' True'.

So the length of "{:>5}".format(str(bool_value)) is alway 5, no matter bool_value is True or False.

Of course you may change the length or the alignment direction as you want. eg. "{:6}".format(str(True)) outputs 'True '.

edited Apr 12, 2016 at 13:17

answered Apr 12, 2016 at 13:12

Syrtis Major

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Drako · Accepted Answer · 2016-04-12 12:37:52Z

0

Not sure if I got idea correctly but if some variable x results in True or False, You can write str(x); if not a case, sorry just try explaining Q in more detailed way

answered Apr 12, 2016 at 12:37

Drako

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