Python - show float as a decimal in a print statement

Question

I'm looking at prices of low-capitalization crypto meme coins. I want to format and show as a decimal in the print statement, up about 10 digits. For example, the price of Saitama as shown on CoinGekco is $0.000000100861.

I don't understand if I'm using the Decimal library wrong, or if this is just a print/formatting issue.

from decimal import Decimal
# I think everything after the 7663 is irrelevant, this is a number I'm getting back 
# from a Uniswap API.  It could be the price in ETH, that is my next issue.
price_float = 2.08229530000000007663121204885725199461299350645049344166181981563568115234375E-11
price_decimal = Decimal(str(price_float))
print("float:", price_float) 
print("decimal:", price_decimal)

Results:

float: 2.0822953e-11
decimal: 2.0822953E-11

Desired Results:

float: 2.0822953e-11
decimal: .000000000020822953

But if I try an exponent less than 6 it seems to work:

price_float = 2.08229530000000007663121204885725199461299350645049344166181981563568115234375E-6

Result:

decimal: 0.0000020822953000000003

Update 1 - based on comment/suggestion: Trying the formatting string. So a change to my question, do I need to bother with decimal at all, as long as I'm not adding numbers or maybe doing math on them?

print("float: {:10.14f}".format(price_float))
print("decimal: {:10.14f}".format(price_decimal))

Result:

float: 0.00000208229530
decimal: 0.00000208229530

Does this answer your question? How to format a floating number to fixed width in Python — base12
– base12, Commented Nov 12, 2021 at 0:17
"Decimal" means "base 10". It doesn't mean "not scientific notation". decimal.Decimal internally uses a base 10 representation, but that doesn't mean it won't print in scientific notation. — user2357112
– user2357112, Commented Nov 12, 2021 at 0:17
Writing price_float = 2.08229530000000007663 - never mind all the digits after that - is utterly and completely useless. Floats simply do not store numbers with that many significant digits of precision; turning this float into a Decimal later does not magically restore the lost precision. The only way to get the exact number into Decimal form is to pass it directly as a string. — jasonharper
– jasonharper, Commented Nov 12, 2021 at 0:26

yoonghm · Accepted Answer · 2021-11-12 00:23:08Z

3

I do that

print(f'{price_float:.20f}')
print(f'{price_float:.20E}')

Output

0.00000000002082295300
2.08229530000000007663E-11

answered Nov 12, 2021 at 0:23

yoonghm

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Comments

base12 · Accepted Answer · 2021-11-12 00:19:57Z

1

You are probably looking for something like print("{:12.10f}".format(price_decimal)). The output format is not controlled here by the decimal library

answered Nov 12, 2021 at 0:19

base12

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