simplify `colorsys.rgb_to_hsv`

[Yay295]

Feature or enhancement

Proposal:

By inlining some variables, the number of operations performed can be reduced. Example:
with

gc = (maxc-g) / rangec
bc = (maxc-b) / rangec

then

h = bc-gc
h = (maxc-b)/rangec - (maxc-g)/rangec
h = ((maxc-b) - (maxc-g)) / rangec
h = (maxc - b - maxc + g) / rangec
h = (g-b) / rangec

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

• gh-124879: simplify colorsys.rgb_to_hsv #124880

[Yay295]

Another optimization could be done here:

cpython/Lib/colorsys.py

Line 142 in 9ce9020

h = (h/6.0) % 1.0

n % 1 is the same as n - floor(n). However, this technically changes the function argument requirements from needing the __mod__ or __rmod__ methods to needing the __floor__ method.

[terryjreedy]

Please look at the rejected issue #114577 and PR #114578 to see if any of the comments are relevant here.

[Yay295]

They are not. That PR did not functionally change colorsys.rgb_to_hsv, but it did replace some ifs with function calls elsewhere, which my change does not do.

[Wulian233]

Please look at the rejected issue #114577 and PR #114578 to see if any of the comments are relevant here.

I remember that😂
My first PR and rejected