DEPR: deprecate Series/DataFrame.compound

[jorisvandenbossche]

xref #18262

Not sure if we need to point to an alternative in the deprecation warning. I can put the exact "formula" for what we are currently calculating, but I don't know enough from finance to know if that is actually good to point to (eg I don't directly see that formula on the first google hit https://en.wikipedia.org/wiki/Compound_interest)

[topper-123]

I'm +1 on deprecating this, as a scalar verion of compount is not particularly useful (I'm an economist).

But also, compound interests arrays can be a bit tricky to calulate in some cases. Would there be acceptance for adding e.g. cumpct_change to mirror cumsum etc.?

[jorisvandenbossche]

Thanks, good to have feedback of somebody who knows something about it! :)

Would there be acceptance for adding e.g. cumpct_change to mirror cumsum etc.?

Personally, I would say, that looks a a bit too specific (but yeah, I would never use it myself). Maybe we should think about making it easier to do generic cumulative operations.

[jorisvandenbossche]

Maybe we should think about making it easier to do generic cumulative operations.

Actually, that's expanding no?

[codecov]

Codecov Report

Merging #26405 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #26405      +/-   ##
==========================================
+ Coverage   91.69%   91.69%   +<.01%     
==========================================
  Files         174      174              
  Lines       50743    50745       +2     
==========================================
+ Hits        46527    46529       +2     
  Misses       4216     4216

Flag	Coverage Δ
#multiple	90.2% <100%> (ø)	⬆️
#single	41.19% <0%> (-0.14%)	⬇️

Impacted Files	Coverage Δ
pandas/core/generic.py	93.49% <100%> (+0.14%)	⬆️
pandas/io/gbq.py	78.94% <0%> (-10.53%)	⬇️
pandas/core/frame.py	97.02% <0%> (-0.12%)	⬇️
pandas/util/testing.py	90.7% <0%> (+0.1%)	⬆️

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[codecov]

Codecov Report

Merging #26405 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #26405      +/-   ##
==========================================
- Coverage   91.69%   91.68%   -0.01%     
==========================================
  Files         174      174              
  Lines       50739    50741       +2     
==========================================
+ Hits        46523    46524       +1     
- Misses       4216     4217       +1

Flag	Coverage Δ
#multiple	90.19% <100%> (ø)	⬆️
#single	41.16% <0%> (-0.16%)	⬇️

Impacted Files	Coverage Δ
pandas/core/generic.py	93.49% <100%> (+0.14%)	⬆️
pandas/io/gbq.py	78.94% <0%> (-10.53%)	⬇️
pandas/core/frame.py	97.02% <0%> (-0.12%)	⬇️

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[jreback]

lgtm. can you add a whats new note & add to the deprecated issue tracker

[jorisvandenbossche]

Added whatsnew

[Davdav05]

Hey guys, as you mentioned there is no alternative suggested. I've been using this method for a while, what would be the shortest/cleanest way to replace this method on a Series?

Thanks!

[jreback]

it’s just

(1 + s).prod() - 1