I was doing a coding assignment recently, and noticed the provided package’s unique function didn’t specify whether it kept only the first item in every consecutive region of equal items. Instilled with a healthy wariness of Undefined Behavior(sidenote:1nasal demons!!), I didn’t want to assume it did so, even though that’s the usual interpretation of that function. It was even more eye-raising because this was a library for parallel operations, so there could have presumably been some weird out-of-order shenanigans going on(sidenote:2Divide and conquer doesn’t consider items sequentially.) that cause it to take arbitrary items in every consecutive region. Equality is associative, after all—maybe something could cook wrt that?
After some tests and double checking the source code, it turned out to keep the first, anyway. Neat.
I remembered this being a problem when I browsed the corresponding Rust documentation before. So, since I’m getting nerd sniped, here’s a lit review:
- C++: specified (
std::unique) - Rust: not specified(sidenote:3This sent me forum hunting/testing at least once before) (
Vec::dedup) - R: doesn’t specify the default behavior, but has a parameter that lets it keep the rightmost item instead, which implies the default is to keep the leftmost, LMAO, hilarious secret third option (
base::unique) - Python (and a few others): doesn’t… seem to exist? The internet keeps saying “roll your own”
The R specificity issue in particular reminded me of a hot take blog post I read on never using checkboxes: https://www.teamten.com/lawrence/programming/checkboxes/. It’s pretty good. I recommend reading it.(sidenote:4I ran into this myself when using an imposer and got confused by a “Alternate Page Rotation (AKA Flip on Long Side)” checkbox. Applying the post’s principles, I would’ve been theoretically less confusing if it was phrased as “printer page rotation: ☐ Flip on short side (standard page rotation) ☐ Flip on long side (alternating page rotation)”)
While trying to find the article again, I also found this similar post on toggle buttons: https://axesslab.com/toggles-suck/. Toggles and checkboxes both represent boolean states, but toggles might worse, it seems.