A Julia package for concatenating, growing, and shrinking arrays in ways that allow control over the resulting axes.
These vectors can grow or shrink from either end, and the axes update correspondingly. In this demo, pay careful attention to the axes at each step:
julia> using CatIndices
julia> v = BidirectionalVector(rand(3))
CatIndices.BidirectionalVector{Float64} with indices CatIndices.URange(1,3):
0.32572
0.250426
0.834728
julia> append!(v, rand(2))
CatIndices.BidirectionalVector{Float64} with indices CatIndices.URange(1,5):
0.32572
0.250426
0.834728
0.388788
0.282573
julia> prepend!(v, rand(3))
CatIndices.BidirectionalVector{Float64} with indices CatIndices.URange(-2,5):
0.992902
0.849368
0.189849
0.32572
0.250426
0.834728
0.388788
0.282573
julia> pop!(v)
0.28257294456774673
julia> axes(v)
(CatIndices.URange(-2,4),)
julia> popfirst!(v)
0.9929020233076613
julia> axes(v)
(CatIndices.URange(-1,4),)deleteat! and insert! are not supported, since it is unclear
whether it should shrink/grow from the beginning or end. To eliminate
many items at the beginning or end of the vector, this package exports
deletehead!(v, n) and deletetail!(v, n).
This is still mostly a TODO. For one-dimensional arrays (AbstractVectors),
PinIndices provides a convenient interface for specifying which indices "win":
julia> v = vcat(1:3, PinIndices(4:5), 6:10)
10-element OffsetArray(::Array{Int64,1}, -2:7) with eltype Int64 with indices -2:7:
1
2
3
4
5
6
7
8
9
10
julia> v[1]
4The array wrapped in PinIndices keeps its own indexes, and everything else adjusts to compensate.