How can I print many significant figures in Python?

Question

For a scientific application I need to output very precise numbers, so I have to print 15 significant figures. There are already questions on this topic here, but they all concern with truncating the digits, not printing more.

I realized that the print function converts the input float to a 10 character string. Also, I became aware of the decimal module, but that does not suit my needs.

So the question is, how can I easily print a variable amount of signifcant figures of my floats, where I need to display more than 10?

Answer 1

Let:

>>> num = 0.0012345 

For 3 significant figures:

>>> f'{num:.3}' '0.00123' 

For 3 decimal places:

>>> f'{num:.3f}' '0.001' 

See the "presentation types for floating point and decimal" table at the bottom of this section for any additional requirements provided by e, E, f, F, g, G, n, %, None.