Indexing a list with a list

I know this is not officially supported, but I was wondering if anyone had any clever workarounds for building an array out of multiple lists.

I built a correctness checker that determines if a student’s graph intersects various circles. However, the method I used requires me to write the index for each circle… which works, but ideally it would be more condensed using the length of the list. That way I can add as many circles as I need without adding more correctness checkers.

https://www.desmos.com/calculator/4o2eqdyzcx

I don’t have a solution in general, but you can resolve the difficulty in your graph by creating a function where the inputs act as the index of checker values. See array no- fail to see how I modified your code.

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Very nice! I had already setup to use it as an index, but I did not think to create it as it’s own function. I was also able to extend it more generally by using summation / integral.

I know this is old, but you could do something similar to what I did with this Dot Grid. First, create a concatenated list (A) of X repeated length(Y) times. Then, create list B from list Y repeated length(X) times, and order this list. Now, (A,B) will be all combinations of an XY array.

https://www.desmos.com/calculator/tp2lsxdmkk

If you need a specific index (X,Y) it would be (Y-1)length(X)+X

Here’s what I came up with. Hope it still might be useful for something else.

Pseudo Array using two lists

Thanks for sharing.

I have had a need for a “pseudo array” on several occasions for different activities I built. I can’t think of one off the top of my head at the moment, but I will surely refer back to this when the time inevitably comes.