# How would I separate a vector into groups where the values are close?

Say I have a vector

``````v = [vcat(1:10); vcat(24:4:40); vcat(500:10:560); vcat(1000:2:1020)]
``````

The values have a wide range but there are groups where the values are close to each other. How would I seperate these groups into individual vectors?

It depends on what you mean by “close”. Do you have a specific rule in mind?

Some number. In this case 11.

Sorry, 11 what? I don’t understand

``````julia> function splitgroups(v)
start = firstindex(v)
groups = typeof(v)[]
for stop in [findall(diff(v) .> 10); lastindex(v)]
push!(groups, @view(v[start:stop]))
start = stop + 1
end
groups
end
splitgroups (generic function with 1 method)

julia> splitgroups(v)
4-element Vector{Vector{Int64}}:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[24, 28, 32, 36, 40]
[500, 510, 520, 530, 540, 550, 560]
[1000, 1002, 1004, 1006, 1008, 1010, 1012, 1014, 1016, 1018, 1020]
``````

This checks for places where the difference between numbers becomes greater than 10, and splits at those places.

It avoids allocating memory for the new vectors by using `@view`, so the original vector `v` will be changed if the contents of these change. If the original vector `v` also will still be used, and you want them to be independent of each other, you can remove the `@view` at the cost of some performance.

Thank you, that’s exactly it. But you missed the last group?

``````function splitgroups(v)
start = firstindex(v)
groups = typeof(v)[]
for stop in findall(diff(v) .> 10)
push!(groups, @view(v[start:stop]))
start = stop + 1
end
push!(groups, @view(v[start:end]))
groups
end
``````

Oh, right. I’ve edited the code to fix it, but your way also works. The way I’ve done it does a small allocation for the sake of avoiding code duplication (of the `push!`) line, which is the way I prefer it.

Edit: You can leave your post also up, it would be useful as a slightly different solution for others who might need it.