Extract specific values from cell based on array in MATLAB

Question

I want to extract some certain values from a simple cell-array, which looks like:

CellExample{1} = [1,54,2,3,4]
CellExample{2} = [1,4,1,92,9,0,2]
...

And I have an additional array that tells me which element I want to extract from each Cell element. The array is as long as the cell:

ArrayExample = [2,4,...]

Basically, I want an array that says:

Solution(1) = CellExample{1}(ArrayExample(1)) = 54
Solution(2) = CellExample{2}(ArrayExample(2)) = 92

I have thought of using cellfun, but I have still some troubles using it correctly, e.g.:

cellfun(@(x) x{:}(ArrayExample),CellExample,'UniformOutput',false)

Isn't your solution(1) supposed to be 54? or am I missing something? — Thomas Ibbotson
– Thomas Ibbotson, Commented Feb 10, 2016 at 13:56
cellfun() already passes the content of the cell to the anonymous function, hence no need for {:} — Oleg
– Oleg, Commented Feb 10, 2016 at 13:57
Start with a loop, there's nothing wrong with using a loop. Have something functional first, worry about making it pretty/efficient later. — sco1
– sco1, Commented Feb 10, 2016 at 13:59
@Oleg, you're right - actually, I just found that out by using the debugger - however, I still can't pass the right values from the array — Jonas
– Jonas, Commented Feb 10, 2016 at 13:59

Oleg · Accepted Answer · 2016-02-10 14:02:21Z

4

The following

Cell{1} = [1,54,2,3,4]
Cell{2} = [1,4,1,92,9,0,2]

cellfun(@(x) disp(x), Cell)

is equivalent to the loop

for ii = 1:numel(Cell)
    disp(Cell{ii})
end

that is, cellfun() already passes the content of each cell to the anonymous function.

However, since you want to pass a numeric array as the second input to the anonymous function, and cellfun() accepts only cell() inputs, you need to use arrayfun(), which does NOT unpack cell content.

In your case:

arrayfun(@(c,pos) c{1}(pos), Cell, Array)

and it is equivalent to:

for ii = 1:numel(Cell)
    Cell{ii}(Array(ii))
end

edited Feb 10, 2016 at 14:02

answered Feb 10, 2016 at 13:59

Oleg

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1 Comment

Jonas Over a year ago

thanks a lot for 1) helping me to understand cellfun better and 2) a simple solution that I was looking for.

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