Display a number in scientific notation with specific digits

Question

i want to display numbers in scientific notation:

-407.45833

So far i used this:

        i = '%E' % Decimal(i)

result:

-4.074583E+02

now my question: how can i add one more digit so it looks like this:?

-4.074583E+002

I know i should find my answer in the tables from Python string formatting to select the proper format layout, but i cant find it. Can someone tell me the result and where to find it please?

I don't believe there's a function for that...but you can do it manually:( — Taku, Mar 24 '17 at 22:02
@abccd if i change this "%.2E" i get "4.07E+02". i did hope there is something similar for the digits at the end — Vipr0, Mar 24 '17 at 22:08
No, unfortunately not, but why did you need to do that? What happens if it's E+0123? Now there's four digits.... — Taku, Mar 24 '17 at 22:10
i have to fill a text document with numbers like that and they have to have this specific format — Vipr0, Mar 24 '17 at 22:18
have you looked at [this](http://stackoverflow.com/a/9911741/1635109) ? — Shreyas Murali, Mar 24 '17 at 22:46

Taku · Accepted Answer · 2017-03-24T23:51:49.423

There's unfortunately not any direct way using string formatting to have three digits following the +. A easy method to replace it is to use this since what we know is that is exponential forms are all stored as strings, so all the string methods will work on it.

I wrote a little function that takes a regular scientific notation and returns a formatted notation with three digits after the +:

from decimal import Decimal
def pretty(notation, n):
    if '+' in notation:
        return "+".join([notation.split('+')[0],notation.split('+')[1].zfill(n)])
    return "-".join([notation.split('-')[0],notation.split('-')[1].zfill(n)])

i = '%E' % Decimal(-407.45833)
print(pretty(i,3)) # leave three digits

That's great, if it actually helped you, you can mark my answer as accepted by checking the ✅. And have a great day:) — Taku, Mar 25 '17 at 19:22

Display a number in scientific notation with specific digits

1 Answers1