How are booleans formatted in Strings in Python?
PythonBooleanString FormattingPython Problem Overview
I see I can't do:
"%b %b" % (True, False)
in Python. I guessed %b for b(oolean). Is there something like this?
Python Solutions
Solution 1 - Python
>>> print "%r, %r" % (True, False)
True, False
This is not specific to boolean values - %r calls the __repr__ method on the argument. %s (for str) should also work.
Solution 2 - Python
If you want True False use:
"%s %s" % (True, False)
because str(True) is 'True' and str(False) is 'False'.
or if you want 1 0 use:
"%i %i" % (True, False)
because int(True) is 1 and int(False) is 0.
Solution 3 - Python
You may also use the Formatter class of string
print "{0} {1}".format(True, False);
print "{0:} {1:}".format(True, False);
print "{0:d} {1:d}".format(True, False);
print "{0:f} {1:f}".format(True, False);
print "{0:e} {1:e}".format(True, False);
These are the results
True False
True False
1 0
1.000000 0.000000
1.000000e+00 0.000000e+00
Some of the %-format type specifiers (%r, %i) are not available. For details see the Format Specification Mini-Language
Solution 4 - Python
To update this for Python-3 you can do this
"{} {}".format(True, False)
However if you want to actually format the string (e.g. add white space), you encounter Python casting the boolean into the underlying C value (i.e. an int), e.g.
>>> "{:<8} {}".format(True, False)
'1 False'
To get around this you can cast True as a string, e.g.
>>> "{:<8} {}".format(str(True), False)
'True False'
Solution 5 - Python
Referring to Python string interpolation
In Python 3.6, string interpolation has been added with a new string literal f prefix
shouldBeTrue = True
print(f"shouldBeTrue={shouldBeTrue}")
Solution 6 - Python
To expand on the answer by phd, you can do all that without str()-ing your booleans in the format() call. There are some weird tricks you can exploit to do formatting for booleans with the new style of string interpolation. It also works for f-strings.
The bland, trivial case
'{},{}'.format(True, False) # 'True,False'
f'{True},{False}' # 'True,False'
Formatting converts booleans to integers
Any padding length will work.
'{:0},{:0}'.format(True, False) # '1,0'
f'{True:0},{False:0}' # '1,0'
'{:>5},{:>5}'.format(True, False) # ' 1, 0'
f'{True:>5},{False:>5}' # ' 1, 0'
String coercion can bring back the normal text
Note the !s in there. This is the most direct equivalent to %s. There's also !r for __repr__() and !a for ASCII, but they're not particularly interesting for booleans.
'{!s:>5},{!s:>5}'.format(True, False) # ' True,False'
f'{True!s:>5},{False!s:>5}' # ' True,False'