# Attempting to create a new list from a list of values and frequencies

I am trying to convert a list of values with frequencies into a single list, so that I can construct boxplots, calculate statistics etc. on the result.

The method I thought of, using a nested list comprehension, failed due to the constraint “List comprehension input list can’t depend on input variable”, so I’m wondering if anyone on this forum has suggestions for how I could accomplish this?

Got it to work using actions.

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Thanks for this interesting solution. I am really keen for something that occurs instantly so as the frequency list changes it can instantly recalculate the underlying list of points.

The only solution I can think of that does this is assuming that X will only have 9 elements and typing out all 9 cases, then joining them.

I don’t know if @Jay can provide any insight into the restriction that the calculator has on list comprehensions here?

Yeah, unfortunately for now the list comprehension variables can’t feed into one another — if they could, I believe your approach would have been solid.

This is what I use: Data from Frequency. The idea is to run a cumulative frequency list (line 2) and then map each data-list index `i` with a datum-index `i_d` and use that to build up the data-list. The mapping is in line 3, something like “find the minimum index where the cumulative frequency exceeds the data-list index.”

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Alternate method! I chatted with Jay off-forum, and he found a way that avoids my messy cumulative frequency index stuff. Here’s the thinking:

Challenge: `[L[i] for i=[1...F[i]], i=[1...length(L)]]` doesn’t work to repeat data value `L[i]` exactly `F[i]` times, because `i` is seen as a free variable for the comprehension.
Solution: Repeat each data value a fixed number of times, then filter down to get the correct number of values!

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Thanks - this is great although I don’t fully understand it at first glance.