How to use string formatting in specific size based variables?

Question

I know that when I use

"%2d"%(x)

I will get a string of x and in at least size of 2, and if the length of x is shorter than 2 I will get spaces before it. But how can I give the 2 as a variable too? For example:

"%nd"%(2,1)
' 1'

Is it possible in Python? Or do I need to create a loop for it?

FWIW the new formatting should work in Python 2.7: '{:>{}}'.format(x, n) — Billy
– Billy, Commented Nov 17, 2016 at 17:19

martineau · Accepted Answer · 2016-11-17 17:42:05Z

1

Use * and the actual width will be read from the next element of the tuple of values, and the value to convert will be the one following:

>>> "%*d" % (2, 1)
' 1'

This is documented in the String Formatting Operations section of the documentation — it says:

Minimum field width (optional). If specified as an '*' (asterisk), the actual width is read from the next element of the tuple in values, and the object to convert comes after the minimum field width and optional precision.

edited Nov 17, 2016 at 17:42

answered Nov 17, 2016 at 17:30

martineau

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1 Comment

Guy Markman Over a year ago

Thank you very much! This is what @vaultah commented an this works!

Moses Koledoye · Accepted Answer · 2016-11-17 17:46:41Z

1

You could choose to be more verbose with the new style formatting:

>>> '{:{width}d}'.format(1, width=2)
' 1'

edited Nov 17, 2016 at 17:46

answered Nov 17, 2016 at 17:20

Moses Koledoye

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martineau Over a year ago

@guy: Actually the new style is a bit more powerful (and easy, once you get the hang of it), so I suggest you take or make the time to learn it.

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