git.net

# Convert a scientific notation to decimal number, and still keeping the data format as float64

```On 10/18/19 9:03 AM, doganadres at gmail.com wrote:
> On Friday, October 18, 2019 at 2:21:34 PM UTC+3, Richard Damon wrote:
>> On 10/18/19 4:35 AM, doganadres at gmail.com wrote:
>>> Here is my question:
>>>
>>>
>>> I am using the numpy.std formula to calculate the standart deviation. However, the result comes as a number in scientific notation.
>>> Therefore I am asking, How to convert a scientific notation to decimal number, and still keep the data format as float64 ?
>>>
>>> Or is there any workaround to get the initial standart deviation result as a decimal number?
>>>
>>>
>>> Here is my code:
>>>
>>> stdev=numpy.std(dataset)
>>> print(stdev)
>>>     Result: 4.999999999999449e-05
>>>
>>>
>>> print(stdev.dtype)
>>>     Result: float64
>>>
>>>
>>> Solutions such as this:
>>>
>>> stdev=format(stdev, '.10f')
>>> converts the data into a string object! which I don't want.
>>>
>>>
>>> Expected result: I am willing to have a result as a decimal number in a float64 format.
>>>
>>> System: (Python 3.7.4 running on Win10)
>>>
>>>
>>> Regards,
>> The number itself isn't in scientific notation or a fixed point number,
>> but is a floating point number that is expressed internally as an
>> integer times a power of 2 (that is the basic representation format for
>> floating point).
>>
>> Scientific notation vs fixed point notation is purely an OUTPUT
>> configuration, not a function on how the number is stored (so in one
>> sense IS more closely linked to a string than the float itself).
>>
>> --
>> Richard Damon
>
> Hello Richard,
>
> You seem so right. But what will we do with those strings with 'e' in it?
>
> There are ways to present those in a 'normal' way with formatting. However, the result of those formatting turns them into str object and which limits you to do any further numerical things with them.
>
> Another thing which I have observed, while doing some experimental thing is that:
>
>>>> 0.0
> 0.0
>
>>>> 0.1
> 0.1
>
>>>> 0.01
> 0.01
>
>>>> 0.001
> 0.001
>
>>>> 0.0001
> 0.0001
>
>>>> 0.00001
> 1e-05
>
> Again another thing with 1e-05! instead of 0.00001 , Is there anything I can do about it?

The 'e' is only part of the string representation presentation of the
value. By default, python decides to present small numbers in
exponential format.? If you don't like that, when you print the numbers
specify the format YOU want, rather than taking the default.

Note, that print() by necessity converts an objects value to a string,
and this conversion for floats uses exponential notation by default for
small numbers. If you don't like it, then use an explicit format for the
conversion.

An alternative might be to change from using a float64 to making it
something like a Decimal.

--
Richard Damon

```