drop trailing zeros from decimal

Question

I have a long list of Decimals and that I have to adjust by factors of 10, 100, 1000,..... 1000000 depending on certain conditions. When I multiply them there is sometimes

Answer 1

Answer is mentioned in FAQ (https://docs.python.org/2/library/decimal.html#decimal-faq) but does not explain things.

To drop trailing zeros for fraction part you should use normalize:

>>> Decimal('100.2000').normalize()
Decimal('100.2')
>> Decimal('0.2000').normalize()
Decimal('0.2')

But this works different for numbers with leading zeros in sharp part:

>>> Decimal('100.0000').normalize()
Decimal('1E+2')

In this case we should use `to_integral':

>>> Decimal('100.000').to_integral()
Decimal('100')

So we could check if there's a fraction part:

>>> Decimal('100.2000') == Decimal('100.2000').to_integral()
False
>>> Decimal('100.0000') == Decimal('100.0000').to_integral()
True

And use appropriate method then:

def remove_exponent(num):
    return num.to_integral() if num == num.to_integral() else num.normalize()

Try it:

>>> remove_exponent(Decimal('100.2000'))
Decimal('100.2')
>>> remove_exponent(Decimal('100.0000'))
Decimal('100')
>>> remove_exponent(Decimal('0.2000'))
Decimal('0.2')

Now we're done.