Is there a function which sorts an array up to a given size?
I know that quicksort divides the array into “halves” every time which should make it easy to get the smallest 1000 in an array of a million values. Does someone already implemented something like this?
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What you want would be select(x, range). It returns sorted elements in x[range] if x is sorted:
julia> x = shuffle(collect(linspace(0, 1, 50)));
julia> select(x, 1:10)
10-element Array{Float64,1}:
0.0
0.0204082
0.0408163
0.0612245
0.0816327
0.102041
0.122449
0.142857
0.163265
0.183673
Note that this function will be renamed to partialsort on Julia 1.0.
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partialsort is definitely the better name 
?
x doesn’t have to be sorted, right? Or maybe I just misunderstand you. Anyway. Thanks 
Oh and is there a function which gives me the indices then?
You’re right. select(x, range) returns the same value of sort(x)[range].
If you want indices, you can use selectperm instead, which will be renamed to partialsortperm on Julia 1.0.
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You can also use sort(..., alg=PartialQuickSort(1000)) to sort the array, and I think you can use sortperm with PartialQuickSort to get the indices.
https://docs.julialang.org/en/stable/stdlib/sort/#Sorting-Algorithms-1
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