Python Convert String to Float without Scientific Notation

Question

I have some code to convert string to float:

n = float('9400108205499941468492')

My unittest throws exceptions:

self.assertEqual(9400108205499941468492, n)

Expected :9400108205499941468492
Actual   :9.400108205499941e+21

What should I do to disable scientific notation in float().

These are equivalent. The way it is displayed is irrelevant. The unit test is failing because you are comparing an int to a float. — Josh Friedlander
– Josh Friedlander, Commented Aug 16, 2022 at 16:50
The problem isn't the scientific notation. The problem is that floats don't have enough precision to represent that number. — Barmar
– Barmar, Commented Aug 16, 2022 at 16:54

Amos Baker · Accepted Answer · 2022-08-16 18:23:09Z

1

As Josh Friedlander mentions you are comparing an int to a float which will always be invalid.

In order to represent a float without scientific notation you can use Decimal but this is also not going to make your comparison to an int valid...

>>> from decimal import Decimal
>>> n = float('9400108205499941468492')
>>> format(Decimal.from_float(n))
'9400108205499941388288'
>>> y = format(Decimal.from_float(n))
>>> type(y)
<class 'str'>

answered Aug 16, 2022 at 18:23

Amos Baker

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Comments

Adrian · Accepted Answer · 2022-08-16 17:15:43Z

0

you can use int() instead of float and when you add 0.5 or any other float then if you want the approximate value then you use int

answered Aug 16, 2022 at 17:15

Adrian

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2 Comments

topcan5 Over a year ago

i believe 9400108205499941468492 is too big for int.

Amos Baker Over a year ago

@topcan5 - Nope >>> x = 9400108205499941468492 >>> x 9400108205499941468492 >>> type(x) <class 'int'>

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