How to print a string at a fixed width?

0x90 picture 0x90 · Dec 9, 2011 · Viewed 259.9k times · Source

I have this code (printing the occurrence of the all permutations in a string)

def splitter(str):
    for i in range(1, len(str)):
        start = str[0:i]
        end = str[i:]
        yield (start, end)
        for split in splitter(end):
            result = [start]
            result.extend(split)
            yield result    

el =[];

string = "abcd"
for b in splitter("abcd"):
    el.extend(b);

unique =  sorted(set(el));

for prefix in unique:
    if prefix != "":
        print "value  " , prefix  , "- num of occurrences =   " , string.count(str(prefix));

I want to print all the permutation occurrence there is in string varaible.

since the permutation aren't in the same length i want to fix the width and print it in a nice not like this one:

value   a - num of occurrences =    1
value   ab - num of occurrences =    1
value   abc - num of occurrences =    1
value   b - num of occurrences =    1
value   bc - num of occurrences =    1
value   bcd - num of occurrences =    1
value   c - num of occurrences =    1
value   cd - num of occurrences =    1
value   d - num of occurrences =    1

How can I use format to do it?

I found these posts but it didn't go well with alphanumeric strings:

python string formatting fixed width

Setting fixed length with python

Answer

0x90 picture 0x90 · Apr 16, 2013

I find using str.format much more elegant:

>>> '{0: <5}'.format('s')
's    '
>>> '{0: <5}'.format('ss')
'ss   '
>>> '{0: <5}'.format('sss')
'sss  '
>>> '{0: <5}'.format('ssss')
'ssss '
>>> '{0: <5}'.format('sssss')
'sssss'

If you want to align the string to the right use > instead of <:

>>> '{0: >5}'.format('ss')
'   ss'

Edit 1: As mentioned in the comments: the 0 in '{0: <5}' indicates the argument’s index passed to str.format().


Edit 2: In python3 one could use also f-string:

sub_str='s'
for i in range(1,6):
    s = sub_str*i
    print(f'{s:>5}')
    
'    s'
'   ss'
'  sss'
' ssss'
'sssss'

or:

for i in range(1,5):
    s = sub_str*i
    print(f'{s:<5}')
's    '
'ss   '
'sss  '
'ssss '
'sssss'

of note, in some places above, ' ' (single quotation marks) were added to emphasize the width of the printed strings.