Vectorized Data Extraction from Cell Array

I have a Nx1 cell array wherein each cell is a #x2 double array (i.e. each array within the cell is of variable length). CellArray{n}(:,1) contains a list of data indecis, while CellArray{n}(:,2) contains values associated with those indecis. I want to get a unique list of all values in that first column from all cells, then perform operations on each value associated with a given data indexi accross all cells, e.g.:

Indecis = unique(CellArray{:}(:,1))
Results = mean(CellArray{:}(Indecis,2))

The above is, of course, not proper MatLab syntax, but I hope it conveys what I'm trying to do. I can achive this rather simply by using cell2mat,

DataMatrix = cell2mat(CellArray);

But whos is telling me that DataMatrix is waaaaaaay bigger than CellArray. As such, I'd like to know if there is a less data/processor intensive way to do this (e.g. cellfun with an annonymous function handle?).

[Matt J]

But whos is telling me that DataMatrix is waaaaaaay bigger than CellArray.

It shouldn't be. It should consume about the same amount of RAM.

[Gabriel Stanley]

aaaaand running it again they returned the approximately the same results. I got confused across multiple iterations of the code which feeds CellArray.

And thinking about it, I don't think there is a better way to do what I'm attempting. Your prior suggestion returned a cell array of the same length as CellArray, whereas what I was loking for was:

Results(:,1) = unique(CellArray{:}(:,1)), i.e. a unique list of all data indecis in the entire CellArray, of type double

and

Results(n,2) = F(CellArray{1}(Results(n,1),2),CellArray{2}(Results(n,1),2),...CellArray{end}(Results(n,1),2))

where F is any function, and the "..." is used in the mathematical sense.

If there are no functions which can handle multiple arrays as a single array without creating a temporary, concatenated copy of those multiple arrays, I think I may be stuck with cell2mat.

[dpb]

Just a nit-picky note that in English, the plural of "index" is "indices"...

[Image Analyst]

@dpb the language has evolved since you and I were young. I think the "ices" may have been a holdover from Latin but now "indexes" has evolved into a perfectly acceptable plural of index. See https://www.dictionary.com/browse/index So both "indices" and "indexes" are correct, however, "indecis" is not correct.

I've also heard that "whom" is going away, in favor of a simpler "who", and maybe considered almost archaic in a few decades, if not already.

https://qz.com/1517643/should-we-let-the-word-whom-die/

https://www.quora.com/Would-you-say-the-word-whom-has-already-become-archaic-or-do-you-think-it-is-still-grammatically-relevant-in-modern-writing

https://www.dailywritingtips.com/who-cares-about-%E2%80%9Cwhom%E2%80%9D-anymore/

Speaking of simplification:

Yay for simpler! 😃