Decimal - remove trailing zeros and supress scientifict notation

Question

I need a function which works like format_float_postional, but doesn't round. It is function which:

should remove trailing zeros
doesn't round (problem with that)
should supress scientifict notation
can be used with Decimal

This is the closesest soultion I found: https://stackoverflow.com/a/58106536/3565923

import numpy as np
formated = np.format_float_positional((float(instance.factor)), trim="-")

Intance factor is a field in serializer. It is Decimal!

class NewConversionSerializer(serializers.ModelSerializer):
    factor = serializers.DecimalField(max_digits=40, decimal_places=20)

At the moment I get: 0.55555555555555555550 -> 0.5555555555555556 I'd want it to be: 0.5555555555555555555

It would be great if both output and input would be decimal.

score 0 · Answer 1 · answered Jun 29 '22 at 11:23

0

d1 = decimal.Decimal("0.555555555555555555555555550")
d2 = decimal.Decimal("0.555555555555555555555555550e-10")
"{:.1000f}".format(d1).rstrip('0')
"{:.1000f}".format(d2).rstrip('0')

Output:

'0.55555555555555555555555555'
'0.000000000055555555555555555555555555'

It works (Python 3.8.10), but it needs a lot more testing in my opinion...

answered Jun 29 '22 at 11:23

Robert Szczelina

41
2

Why not just use `"{:f}"` instead of `"{:.1000f}"`? (Or even better, `format(d1, "f")` or `f"{d1:f}"`.) – Mark Dickinson Jun 29 '22 at 18:41
Default precision for `{":f"}` is 6 – user3565923 Jun 30 '22 at 08:53
precision is 6 for floats, but for Decimal it seems to work as expected – user3565923 Jul 01 '22 at 10:03

Decimal - remove trailing zeros and supress scientifict notation

1 Answers1