How to right-align numeric data?

Question

I have some data that I am displaying in 3 column format, of the form:

key: value key: <tab> key: value <tab> key: value.

Here’s an example:

p: 1    sl: 10  afy: 4
q: 12   lg: 10  kla: 3
r: 0    kl: 10  klw: 3
s: 67   vw: 9   jes: 3
t: 16   uw: 9   skw: 3
u: 47   ug: 9   mjl: 3
v: 37   mj: 8   lza: 3
w: 119  fv: 8   fxg: 3
x: 16   fl: 8   aew: 3

However, I’d like if the numbers were all right aligned, such as:

a:   1
b:  12
c: 123

How can I do this in Python?

Here is the existing printing code I have:

print(str(chr(i+ord('a'))) + ": " + str(singleArray[i]) + "t" +
    str(doubleArray[i][0]) + ": " + str(doubleArray[i][1]) + "t" +
    str(tripleArray[i][0]) + ": " + str(tripleArray[i][1]))

Asked By: samoz

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Source

Answer 1

In Python 2.5 use rjust (on strings). Also, try to get used to string formatting in python instead of just concatenating strings. Simple example for rjust and string formatting below:

width = 10
str_number = str(ord('a'))
print 'a%s' % (str_number.rjust(width))

Answered By: ChristopheD

Answer 2

If you know aa upper bound for your numbers, you can format with "%<lenght>d" % n. Given all those calculations are done and in a list of (char, num):

mapping = ((chr(i+ord('a')), singleArray[i]), 
           (doubleArray[i][0],doubleArray[i][1]), 
           (tripleArray[i][0],tripleArray[i][1])
           )
for row in mapping:
   print "%s: %3d" % row

Answered By: Jochen Ritzel

Answer 3

Use python string formatting: '%widths' where width is an integer

>>> '%10s' % 10
'        10'
>>> '%10s' % 100000
'    100000'

Answered By: Nadia Alramli

Answer 4

In python 2.6+ (and it’s the standard method in 3), the “preferred” method for string formatting is to use string.format() (the complete docs for which can be found here).
right justification can be done with

"a string {0:>5}".format(foo)

this will use 5 places, however

"a string {0:>{1}}".format(foo, width)

is also valid and will use the value width as passed to .format().

Answered By: Colin Valliant

Answer 5

In Python 3.6 you can use Literal String
Interpolation, which is less
verbose and probably more intuitive to use:

width = 5
number = 123
print (f'{number:>{width}}')

Or just:

number = 123
print (f'{number:>5}')

It reuses much of the str.format() syntax.

I guess/hope this will be the prefered way in the future.

Answered By: Torkel Bjørnson-Langen

How to right-align numeric data?

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