问题
I want to fill out a string with spaces. I know that the following works for zero\'s:
>>> print \"\'%06d\'\"%4
\'000004\'
But what should I do when I want this?:
\'hi \'
of course I can measure string length and do str+\" \"*leftover, but I\'d like the shortest way.
回答1:
You can do this with str.ljust(width[, fillchar]):
Return the string left justified in a string of length width. Padding is done using the specified fillchar (default is a space). The original string is returned if width is less than
len(s).
>>> 'hi'.ljust(10)
'hi '
回答2:
Unless you need to support Python 2.5, you can (and probably should) use the string-formatting mini-language, like so:
'{0: <16}'.format('Hi')
回答3:
The new(ish) string format method lets you do some fun stuff with nested keyword arguments. The simplest case:
>>> '{message: <16}'.format(message='Hi')
'Hi '
If you want to pass in 16 as a variable:
>>> '{message: <{width}}'.format(message='Hi', width=16)
'Hi '
If you want to pass in variables for the whole kit and kaboodle:
'{message:{fill}{align}{width}}'.format(
message='Hi',
fill=' ',
align='<',
width=16,
)
Which results in (you guessed it):
'Hi '
回答4:
You can try this:
print "'%-100s'" % 'hi'
回答5:
Correct way of doing this would be to use Python's format syntax as described in the official documentation
For this case it would simply be:'{:10}'.format('hi')
which outputs:'hi '
Explanation:
format_spec ::= [[fill]align][sign][#][0][width][,][.precision][type]
fill ::= <any character>
align ::= "<" | ">" | "=" | "^"
sign ::= "+" | "-" | " "
width ::= integer
precision ::= integer
type ::= "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"
Pretty much all you need to know is there ^.
Update: as of python 3.6 it's even more convenient with literal string interpolation!
foo = 'foobar'
print(f'{foo:10} is great!')
# foobar is great!
回答6:
Use str.ljust():
>>> 'Hi'.ljust(6)
'Hi '
You should also consider string.zfill(), str.ljust() and str.center() for string formatting. These can be chained and have the 'fill' character specified, thus:
>>> ('3'.zfill(8) + 'blind'.rjust(8) + 'mice'.ljust(8, '.')).center(40)
' 00000003 blindmice.... '
These string formatting operations have the advantage of working in Python v2 and v3.
Take a look at pydoc str sometime: there's a wealth of good stuff in there.
回答7:
As of Python 3.6 you can just do
>>> strng = 'hi'
>>> f'{strng: <10}'
with literal string interpolation.
Or, if your padding size is in a variable, like this (thanks @Matt M.!):
>>> to_pad = 10
>>> f'{strng: <{to_pad}}'
回答8:
you can also center your string:
'{0: ^20}'.format('nice')
回答9:
Use Python 2.7's mini formatting for strings:
'{0: <8}'.format('123')
This left aligns, and pads to 8 characters with the ' ' character.
回答10:
Just remove the 0 and it will add space instead:
>>> print "'%6d'"%4
回答11:
Wouldn't it be more pythonic to use slicing?
For example, to pad a string with spaces on the right until it's 10 characters long:
>>> x = "string"
>>> (x + " " * 10)[:10]
'string '
To pad it with spaces on the left until it's 15 characters long:
>>> (" " * 15 + x)[-15:]
' string'
It requires knowing how long you want to pad to, of course, but it doesn't require measuring the length of the string you're starting with.
回答12:
+= can be used to append to string
>>> string = 'hi'
>>> for s in range(0,5):
... string += ' '
...
>>> string
'hi '
回答13:
You could do it using list comprehension, this'd give you an idea about the number of spaces too and would be a one liner.
"hello" + " ".join([" " for x in range(1,10)])
output --> 'hello '
回答14:
A nice trick to use in place of the various print formats:
(1) Pad with spaces to the right:
('hi' + ' ')[:8]
(2) Pad with leading zeros on the left:
('0000' + str(2))[-4:]
来源：https://stackoverflow.com/questions/5676646/how-can-i-fill-out-a-python-string-with-spaces