Add two-argument first and last methods for any iterable
#34868
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giordano
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Thanks! Looks good, apart from one decision to make: should negative indices be allowed or not? Currently they are not allowed for |
Uhm, that comes automatically from the use of |
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We might support this for arbitrary iterators via Iterators.reverse, in which case it would support multidimensional arrays too. |
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@stevengj Do you have an opinion about whether we should allow negative number of elements or not? |
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What would negative numbers of elements mean?
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General iterator definitions: first(itr, n::Integer) = collect(Iterators.take(itr, n))
last(itr, n::Integer) = reverse!(collect(Iterators.take(Iterators.reverse(itr), n)))Might be nice to include something like this too. |
In the current state of the PR they are equivalent to
Yeah, sounds like a good idea. |
This option controls where the vertical lines of the table will be drawn. Closes #46
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Anything we can do to move this forward? Hate to see a PR languishing like this. |
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Ok, I'll get back this weekend |
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{first,last}(::AbstractVector, ::Integer) methodsfirst and last methods for any iterable
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I believe I've addressed all comments above and CI seems happy |
| """ | ||
| first(itr, n::Integer) = collect(Iterators.take(itr, n)) | ||
| # Faster method for vectors | ||
| function first(v::AbstractVector, n::Integer) |
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Why is this method for AbstractVector, but the corresponding specialized last method below is for AbstractArray?
…ng#34868) * Add `{first,last}(::AbstractVector, ::Integer)` methods * Apply suggestions from code review Co-Authored-By: Milan Bouchet-Valat <[email protected]> * Add tests for OffsetArrays * Use `begin` in place of `firstindex` * Generalise two-argument `first` and `last` to any iterable Co-authored-by: Milan Bouchet-Valat <[email protected]>
* improve first/last docstrings improve `first`/`last` docstrings to indicate that two new methods have been added since v1.6 (#34868) * Update abstractarray.jl remove the trailing whitespaces
* improve first/last docstrings improve `first`/`last` docstrings to indicate that two new methods have been added since v1.6 (JuliaLang#34868) * Update abstractarray.jl remove the trailing whitespaces
* improve first/last docstrings improve `first`/`last` docstrings to indicate that two new methods have been added since v1.6 (JuliaLang#34868) * Update abstractarray.jl remove the trailing whitespaces
For reference: https://discourse.julialang.org/t/extend-last-to-also-work-with-arrays/35100.
Contrary to what was asked in the discourse thread, this only applies to vectors, as I think this is the most uncontroversial option. If applied to a generic array, the first/last n elements would be flattened, which may or may not what users expect.