Question

I am wondering how to truncate numbers in Python 3? For example, 87.28197 to 87.281
The standard in Python 2 was using % but this is no longer used.

Answer 1

The % string formatter still is available in Python 3. It is preferred you use the ''.format() string formatting syntax, which also supports specifying float precisions.

Both of these work:

>>> yournumber = 87.28197
>>> "{0:.3f}".format(yournumber)
'87.282'
>>> "%.3f" % yournumber
'87.282'

If it is just the one float you are converting to a string, then the format() function is probably more convenient as you do not need to use a {0:..} placeholder:

>>> format(yournumber, '.3f')
'87.282'