0-based Indexing in Julia

This is one of the submission blog post for the ongoing Google Code-in competition. This year I was mainly concentrating on Julia tasks. I think you get to learn much more when you stick to one org. While looking through the tasks I found this one where we have to explain that we can do 0-based indexing in Julia.

For those who are not familiar with Julia, it has 1-based indexing. Hence, all the arrays, vectors start from 1 rather than from 0 (as in many other programming languages). Initially, I didn't think if it was much of a deal, since I never actually thought people would judge the programming language based on whether it has a 0-based on 1-based indexing.

But, to my surprise I saw the comments on this post on reddit and that made up my mind to do this task. So, there are a lot of things Julia docs says about indexing, and yeah sometimes it might just be possible that the 0-based indexing is better then 1-based.

I'm just writing here about how you can implement 0-based indexing using OffsetArrays.jl. Along with the relative indexing it offers many other features which you may want from Julia but are not available out of the box.

For this task, we are concerned about the 0-based indexing and in order to do that you can simply declare an OffsetArray in the following manner:

julia> using OffsetArrays

julia> x = OffsetArray([1, 2, 3], 0:2)
3-element OffsetArray(::Array{Int64,1}, 0:2) with eltype Int64 with indices 0:2:

Here I'm just creating a vector with the values 1, 2, 3 with a relative indexing of 0 to 2. Hence, if I ran:

julia> x[0]

or if I ran:

julia> x[2]

or even this:

julia> x[end]

it would work just as you'd expect from a 0-based indexed vector.

I feel this blog post was more designed to make people aware that they can do 0-based indexing if they want. There are many packages which can help you with your task.

I hope this helped. Thank you :)