How to control decimals of a float in formatted string

Question

Recently I came upon this awesome way to prevent python from converting floats to scientific notation:

start = 0.000005
a = f'{start:.10f}'
print(a)

Output:

0.0000050000

I was wondering if there is an automated way to determine how many decimals the number has instead of providing the amount yourself .10f so I can get this output:

0.000005

Answer 1

You can use the rstrip method to remove the zeros on the right:

start = 0.000005
a = f'{start:.10f}'.rstrip('0')
print(a)
# 0.000005

In case you have no decimal part, it could be better to also remove the '.' when there is no zero left:

start = 5.00000
a = f'{start:.10f}'.rstrip('0').rstrip('.')
print(a)
# 5

Answer 2

just use print(f'{start:f}) without specyfing how many decimal points you want