I've some lists and more complex structures containing floats. When printing them, I see the floats with a lot of decimal digits, but when printing, I don't need all of them. So I would like to define a custom format (e.g. 2 or 3 decimals) when floats are printed.
I need to use floats and not Decimal. Also, I'm not allowed to truncate/round floats.
Is there a way to change the default behavior?
>>> a = 0.1
>>> a
0.10000000000000001
>>> print a
0.1
>>> print "%0.3f" % a
0.100
>>>
From the Python docs, repr(a) would give 17 digits (as seen by just typing a at the interactive prompt, but str(a) (automatically performed when you print it) rounds to 12.
Edit: Most basic hack solution... You have to use your own class though, so...yeah.
>>> class myfloat(float):
... def __str__(self):
... return "%0.3f" % self.real
>>> b = myfloat(0.1)
>>> print repr(b)
0.10000000000000001
>>> print b
0.100
>>>