How do I left-align numbers in columns in Python?

Question

I am trying to write a function that passes this doctest:

Prints a table of values for i to the power of 1,2,5 and 10 from 1 to 10
left aligned in columns of width 4, 5, 8 and 13
>>> print_function_table()
i   i*2 i*5    i*10
1   1    1       1
2   4    32      1024
3   9    243     59049
4   16   1024    1048576
5   25   3125    9765625
6   36   7776    60466176
7   49   16807   282475249
8   64   32768   1073741824
9   81   59049   3486784401
10  100  100000  10000000000

I feel like I am almost there but I can't seem to left-align my columns.

the code i have is:

def print_function_table():
    i = 1
    s = "{:^4} {:^5} {:^8} {:^13}"
    print s.format("i", "i*2", "i*5", "i*10")
    while i <= 10:
        print s.format(i, i*2, i*5, i*10)
        i += 1

Side note: Use for i in range(1, 11): instead of a while loop. — Marcelo Cantos
– Marcelo Cantos, Commented May 18, 2011 at 5:08
Side note 2: Why require left-alignment, when right-alignment is easier and more readable? — Marcelo Cantos
– Marcelo Cantos, Commented May 18, 2011 at 5:09

ubik · Accepted Answer · 2011-05-21 17:20:15Z

5

What about...

def print_function_table():
    s = "{:<4} {:<5} {:<8} {:<13}"
    print s.format("i", "i*2", "i*5", "i*10")
    for i in range(1,11):
        print s.format(i, i**2, i**5, i**10)

?

answered May 21, 2011 at 17:20

ubik

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4 Comments

Joël Over a year ago

Note: "{} {}".format() is valid starting with Python 3.1+; for previous versions one should use "{0} {1}".format() (with explicit indexes), see docs.python.org/py3k/library/string.html §6.1.3.2.

Kos Over a year ago

@Joël Not really true, current python 2.7.3 doc mentions this too. Py3k features like to be backported

Arnab Datta Over a year ago

this would be prettier with eval instead of repeating the header :)

ubik Over a year ago

@ArnabDatta Maybe it'd look pretty, but for sure less clear as well.

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