How can I fill out a Python string with spaces?

Question

I want to fill out a string with spaces. I know that the following works for zero\'s:

>>> print  \"\'%06d\'\"%4
\'000004\'

But wha

Answer 1

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.

Answer 2

For a flexible method that works even when formatting complicated string, you probably should use the string-formatting mini-language, using either the str.format() method

>>> '{0: <16} StackOverflow!'.format('Hi')  # Python >=2.6
'Hi               StackOverflow!'

of f-strings

>>> f'{"Hi": <16} StackOverflow!'  # Python >= 3.6
'Hi               StackOverflow!'

Answer 3

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.

Answer 4

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!

Answer 5

you can also center your string:

'{0: ^20}'.format('nice')

Answer 6

Just remove the 0 and it will add space instead:

>>> print  "'%6d'"%4