Round float to 2 digits after dot in python

Question

I'm using this code:

f = 0.3223322
float('%.2f' % (f))

Is there more pythonic, less verbose method without 2 castings? Using round is discouraging by the following note from the documentation

The behavior of round() for floats can be surprising: for example, round(2.675, 2) gives 2.67 instead of the expected 2.68. This is not a bug: it’s a result of the fact that most decimal fractions can’t be represented exactly as a float. See Floating Point Arithmetic: Issues and Limitations for more information.

Answer 1

round(number[, ndigits]):

>>> round(0.3223322, 2)
0.32

Note that you’ll probably still want to use a certain precision of string formatting when producing output due to floating point imprecision.

Depending on what you’re trying to achieve, it might be appropriate to use the Decimal type:

>>> from decimal import Decimal
>>> round(Decimal(0.3223322), 2)
Decimal('0.32')

which does its math in (surprise!) decimal instead of binary and therefore doesn’t suffer any issues with decimal rounding (except initially if you’re trying to create it from a float).

Answer 2

This is not as nice, but I'm always a fan of:

f=float(int(100*f))/100

Far from the best way to do it, but it's one I use often.