ENH: Add units to scipy.constants description

[BenediktBurger]

Is your feature request related to a problem? Please describe.

I could not find out, in which units the constants of scipy.constants are.
I guess they are in SI notation, but I'd like to be sure, before I use these numbers.

Describe the solution you'd like.

Could you add either a general note, that all the constants are given in base units of the SI system, or add to every constant the relavant units (e.g. speed of light in vacuum in meters/second).

Describe alternatives you've considered.

No response

Additional context (e.g. screenshots, GIFs)

No response

[tupui]

Hi @bmoneke, thank you for reporting. Units are in the doc here https://docs.scipy.org/doc/scipy/reference/constants.html

Is there something missing? (scroll down). Otherwise yes, everything is in SI and yes maybe we can add a note at the beginning to make it clear. Would you like to do it?

[BenediktBurger]

Below are the constants with units, but the "base constants" are not labelled.

I can do it.

I'll add a general note at the beginning.

What do you think about writing to every constant (in that list) the unit as well? Just as a reminder for the readers.

[tupui]

Spelling out all constants, as done for the rest, is a good idea 👍

(If you are looking into making changes to this doc. There is a stalled PR that wanted to change the organisation etc #11682. If you are interested, it would be great to pick up 😃)

Thanks!

[tupui]

@bmoneke maybe hold on a bit here. As you can see in #11682 some work might start again. In any case, thank you for raising this as it helped move things!

[BenediktBurger]

I saw that other point, when I searched for open/closed issues before opening my own one.

Thanks for your fast responses.

[jakobjakobson13]

@bmoneke : Could you answer me two questions for clarification?

Below are the constants with units, but the "base constants" are not labelled.

The base constants are included in the CODATA constants provided by scipy but the base constants are not emphasized explicitly. So you are right, they can be easily overlooked.
Do you want to list the base constants in an dedicated section or do you want to just emphasize them? In the first case they would be listed twice (which I would neither consider ideal) whereas the second case will not be easy to implement.

[BenediktBurger]

@jakobjakobson13 , thanks for the question.

I just want to know the units next to the name. They don't have to be emphasized.

Here my problem: I imported the package and found c = 3e8 (approximately). Then I try to figure out, what the unit of that c is and I don't find anything in the documentation.
The documentation regarding CODATA did not help either, as the same constant is included several times (e.g. Boltzmann constant), albeit in different units. Which of these is now the directly imported value?

I cannot use a constant without knowing, that the units fit.

Maybe a (bold) remark, that these base constants are the numbers in the SI system might be enough and a small change. However, being explicit about the units is better, I think.

I hope I succeeded in showing my problem.

[jakobjakobson13]

Congratulations, you picked a nice corner case here :)
By loading the scipy.constants module some constants are currently imported automatically.

scipy/scipy/constants/__init__.py

Line 325 in 5da8a3a

from ._constants import *

Among these constants is c or the speed of light in vacuum.

scipy/scipy/constants/_constants.py

Line 109 in 5da8a3a

c = speed_of_light = _cd('speed of light in vacuum')

The problem now is however that _cd only imports the value but not the unit.

scipy/scipy/constants/_constants.py

Line 15 in 5da8a3a

from ._codata import value as _cd

scipy/scipy/constants/_codata.py

Line 1575 in 5da8a3a

def value(key: str) -> float:

If you had imported the constant via scipy.constants.physical_constants you would have had the constant with its value AND its unit. I hope that helps to your understanding.

[BenediktBurger]

Thanks for your explanation. Maybe you can use my experience during your adjustments, in order to make it more understandable, how to use it.