Question

I have a large array, h, that contains several instances of a parameter called startingParam, which is always followed by two other parameters that are related but not always the same. I need to look for every instance of startingParam in the array, and push it and the next two parameters into a separate array, holdingArray.

The following code is not working, due to the fact that I am very new to Ruby. Does anybody know what I am doing wrong? Is there a better way to approach the problem?

h.each do |param|
    if param == 'startingParam'
        holdingArray << h.[param],
        holdingArray << h.[param + 1],
        holdingArray << h.[param + 2]
    end
end

Thanks so much.

Answer 1

So there are a few problems. For starters, you can’t subscript arrays by doing h.[anything], and you are also subscripting based on the value (and not the index). You are also checking to see if the parameter matches the literal string “starting_param” and not its value. So what I expect you want is the following:

h.each_with_index do |param, index|
  if param == startingParam
    holdingArray << h[index]
    holdingArray << h[index+1]
    holdingArray << h[index+2]
  end
end

You’ll also note that if the item is in the last two slots of the array, this will wrap around and grab items from the beginning of the array (due to how Ruby handles array subscripts being out of bounds).