Timeline for Get the first item from an iterable that matches a condition
Current License: CC BY-SA 4.0
16 events
| when toggle format | what | by | license | comment | |
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| Nov 23, 2023 at 20:28 | comment | added | Puff | I guess I'm just biased by my most comon usecase. | |
| Nov 22, 2023 at 16:31 | comment | added | Caridorc | @Puff but why test all if we only care about the first? Also vectorized use case is much more specialized | |
| Nov 21, 2023 at 20:19 | comment | added | Puff | I'd argue a better default value for condition is Bool. I think it will reduce overhead in the cases where the iterable is an array that supports vectorized functions. In that case, the user can test for the condition on the whole array at once and pass that to the function. Depending on when the condition is fulfilled and the size of the array, that may be preferred. | |
| Apr 11, 2021 at 23:31 | comment | added | brandonscript |
Yep! The other thing you'll want to do here is test whether condition exists before trying to write a condition; sometimes even returning x at all from an iterator could be expensive (e.g., if x is a generator yield). So check if condition otherwise just return next(x for x in iterable, default)
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| Apr 11, 2021 at 23:28 | comment | added | Caridorc | @brandonscript interesting I did not know about that | |
| Apr 10, 2021 at 4:39 | comment | added | brandonscript |
why would you not just use the built-in default functionality of next()? next(x for x in iterable if condition(x), default)
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| Mar 9, 2020 at 21:23 | comment | added | Caridorc | @Zorf I added an alternative version with a default argument | |
| Mar 9, 2020 at 21:22 | history | edited | Caridorc | CC BY-SA 4.0 |
added version with default argument
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| Feb 26, 2020 at 22:39 | comment | added | Zorf | There should be an optional default argument, and if that argument not be supplied, only then raise an exception when no element in the sequence satisfy the condition. | |
| May 25, 2018 at 12:45 | comment | added | Guy | Baldrickk I feel like this isn't an iteration method. You won't call this one in a contest of an iterator. But I'm not feeling too strongly about it :) | |
| May 24, 2018 at 7:51 | comment | added | Baldrickk |
@guyarad StopIteration is the canonical "out of elements" exception in python. I don't see a problem with it being thrown. I'd probably use a default of "None" which can be passed in as a default parameter to the function.
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| Feb 5, 2018 at 8:25 | comment | added | Guy |
no... I just "invented" an exception. If you are implementing a first function, having it raise a StopIteration exception just seems weird. Anyway, take a look at boltons.iterutils.first.
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| Jan 28, 2018 at 11:22 | comment | added | Caridorc | @guyarad Is that a kind of ValueError? | |
| Jan 26, 2018 at 3:28 | comment | added | Guy | If you are wrapping it with a method, at least catch StopIteration and raise EmptySequence error. Would be much prettier when there are no elements. | |
| Feb 19, 2016 at 19:31 | history | edited | Caridorc | CC BY-SA 3.0 |
added exceptional scenario description and test
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| Feb 19, 2016 at 19:25 | history | answered | Caridorc | CC BY-SA 3.0 |