How to print a string at a fixed width?
Solution 1
EDIT 2013-12-11 - This answer is very old. It is still valid and correct, but people looking at this should prefer the new format syntax.
You can use string formatting like this:
>>> print '%5s' % 'aa'
aa
>>> print '%5s' % 'aaa'
aaa
>>> print '%5s' % 'aaaa'
aaaa
>>> print '%5s' % 'aaaaa'
aaaaa
Basically:
- the
%
character informs python it will have to substitute something to a token - the
s
character informs python the token will be a string - the
5
(or whatever number you wish) informs python to pad the string with spaces up to 5 characters.
In your specific case a possible implementation could look like:
>>> dict_ = {'a': 1, 'ab': 1, 'abc': 1}
>>> for item in dict_.items():
... print 'value %3s - num of occurances = %d' % item # %d is the token of integers
...
value a - num of occurances = 1
value ab - num of occurances = 1
value abc - num of occurances = 1
SIDE NOTE: Just wondered if you are aware of the existence of the itertools
module. For example you could obtain a list of all your combinations in one line with:
>>> [''.join(perm) for i in range(1, len(s)) for perm in it.permutations(s, i)]
['a', 'b', 'c', 'd', 'ab', 'ac', 'ad', 'ba', 'bc', 'bd', 'ca', 'cb', 'cd', 'da', 'db', 'dc', 'abc', 'abd', 'acb', 'acd', 'adb', 'adc', 'bac', 'bad', 'bca', 'bcd', 'bda', 'bdc', 'cab', 'cad', 'cba', 'cbd', 'cda', 'cdb', 'dab', 'dac', 'dba', 'dbc', 'dca', 'dcb']
and you could get the number of occurrences by using combinations
in conjunction with count()
.
Solution 2
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'
In case 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-strings:
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.
Solution 3
Originally posted as an edit to @0x90's answer, but it got rejected for deviating from the post's original intent and recommended to post as a comment or answer, so I'm including the short write-up here.
In addition to the answer from @0x90, the syntax can be made more flexible, by using a variable for the width (as per @user2763554's comment):
width=10
'{0: <{width}}'.format('sss', width=width)
Further, you can make this expression briefer, by only using numbers and relying on the order of the arguments passed to format
:
width=10
'{0: <{1}}'.format('sss', width)
Or even leave out all numbers for maximal, potentially non-pythonically implicit, compactness:
width=10
'{: <{}}'.format('sss', width)
Update 2017-05-26
With the introduction of formatted string literals ("f-strings" for short) in Python 3.6, it is now possible to access previously defined variables with a briefer syntax:
>>> name = "Fred"
>>> f"He said his name is {name}."
'He said his name is Fred.'
This also applies to string formatting
>>> width=10
>>> string = 'sss'
>>> f'{string: <{width}}'
'sss '
Solution 4
format
is definitely the most elegant way, but afaik you can't use that with python's logging
module, so here's how you can do it using the %
formatting:
formatter = logging.Formatter(
fmt='%(asctime)s | %(name)-20s | %(levelname)-10s | %(message)s',
)
Here, the -
indicates left-alignment, and the number before s
indicates the fixed width.
Some sample output:
2017-03-14 14:43:42,581 | this-app | INFO | running main
2017-03-14 14:43:42,581 | this-app.aux | DEBUG | 5 is an int!
2017-03-14 14:43:42,581 | this-app.aux | INFO | hello
2017-03-14 14:43:42,581 | this-app | ERROR | failed running main
More info at the docs here: https://docs.python.org/2/library/stdtypes.html#string-formatting-operations
Solution 5
>>> print(f"{'123':<4}56789")
123 56789
![0x90](https://i.stack.imgur.com/xlhE1.jpg?s=256&g=1)
0x90
echo \[q\]sa\[ln0=aln256%Pln256/snlbx\]sb3135071790101768542287578439snlbxq|dc
Updated on July 29, 2022Comments
-
0x90 almost 2 years
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:
-
TJD over 12 yearswhat about print '%10s' % 'mystring'
-
Admin over 6 yearsSurprised that
"\t"
is not listed as an option in any solution.
-
-
tripleee over 11 yearsYou should perhaps mention that negative numbers give left-justified padded output; this is hardly intuitive for a beginner.
-
mightypile over 10 yearsAdditionally, the 0 indicates the position of the format argument, so you can do two other things:
'{<5}'.format('ss')
'ss '
just like before, but without the 0, does the same thing or'Second {1: <5} and first {0: <5}'.format('ss', 'sss')
'Second sss and first ss '
so you can reorder or even output the same variable many times in a single output string. -
mightypile over 10 yearsI can no longer edit the previous comment, which needs it.
{<5}
does not work, but{: <5}
does work without the index value. -
Brian Wylie over 10 years+1 for @tripleee, without your negative numbers give left-justified comment I would have been hitting my head longer... thx m8.
-
scottmrogowski about 10 yearsThis is far more intuitive and concise than the new str.format. I don't understand why there is this push in python towards convolution
-
cod3monk3y over 9 yearsHere's the Python Format Specification Mini-Language describing these format strings and additional options. For quick reference, the space in
{0: <5}
is the[fill]
, the<
is[align]
, and5
is[width]
-
gjois over 7 yearsThat 5 can be a variable substitution
>>> print width 20 >>> print "{0: <{width}}".format("ssssss", width=width).split('\n') ['ssssss '] >>>
-
joelostblom over 7 yearsYou can also use numbers and just list the variables in order
width=10; "{0: <{1}}".format('sss', width)
. Or even leave out the numbers'{: <{}}'.format('sss', width)
-
0x90 over 7 years@cheflo please feel welcome to edit the answer itself. Thank you
-
Ziu about 7 years@cod3monk3y if i am not wrong,
{0: <5}
the0
means the first argument but what dose:
do in here? And I can't find the role of:
in the format-specification -
cod3monk3y about 7 yearsThe colon separates the argument
{0}
from the formatting of that argument. It's optional. Seeformat_spec
in the Format String Syntax. From the docs: "The field_name is optionally followed by ... a format_spec, which is preceded by a colon ':'." -
Harshit Jindal about 6 yearsIs there a way to fill in the blank spaces with a specific character? For example, if we need to print "05" instead of " 5"
-
pfabri almost 5 yearsHere are some more tricks for elegant fixed-width printing with f-strings on Medium.
-
xjcl over 4 yearsThis won't shorten strings above 20 characters however. Use
'%(name)20.20s'
which sets 20 both as min and max string length! -
Syrtis Major about 4 yearsI really like this answer most!