Add searchsortednext and searchsortedprevious

[SynapticSage]

Adding searchsortednext and searchsortedprevious

Two common tasks involving finding the nearest point, but not the same: finding the "nearest but greater than point", ie next point, or "nearest but smaller than point", ie previous point. I added two methods for those.

We often use that sort of functionality in animal behavior data when we want a label corresponding to the beginning or the end of a trial.

It's true that one could type searchsortedfirst(search_item .<= sorted_list, true) to find the nearest next point or searchsortedfirst(search_item .<= sorted_list, true) -1 to find the previous. But encountering lines like those in someone else's code can be opaque. Better to have a function that more or less documents the action taken. Hence why it's nice to have these.

It's also worth mentioning that there's some precedence for these modes in other languages. Matlab's interp1 has method=nearest setting, but also next and previous. (see https://www.mathworks.com/help/matlab/ref/interp1.html#btwp6lt-1-method)

[joshday]

Sorry for the delay in reviewing (I'm currently on parental leave). I'll try to take a look before the end of the week.

[SynapticSage]

No rush 👍

(Very minor PR - it can wait.)

[codecov]

Codecov Report

Merging #4 (c043ff5) into main (2f58809) will decrease coverage by 9.10%.
The diff coverage is 85.71%.

@@             Coverage Diff             @@
##              main       #4      +/-   ##
===========================================
- Coverage   100.00%   90.90%   -9.10%     
===========================================
  Files            1        1              
  Lines            8       22      +14     
===========================================
+ Hits             8       20      +12     
- Misses           0        2       +2     

Impacted Files	Coverage Δ
src/SearchSortedNearest.jl	90.90% <85.71%> (-9.10%)	⬇️

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[joshday]

LGTM. Thanks for the PR. I appreciate the rationale and tests!