Build array from descriptive data without a loop

I want to go from

Array1 = [10,3,3;1000,178,4];

to

Array2 = [10;13;16;1000;1178;1356;1534];

without using

Idx2 = 1;
Array2 = zeros(sum(Array1(:,3)),1);
for Idx1 = 1:size(Array1,1)
    Array2(Idx2:Idx2+Array1(Idx1,3)-1) = [Array1(Idx1,1),Array1(Idx1,1)+[1:Array1(Idx1,3)-1].*Array1(Idx1,2)];
    Idx2 = Idx2+Array1(Idx1,3)-1;
end

Help?

Answer 1

[Walter Roberson]

Array1 = [10,3,3;1000,178,4];
Array2 = cell2mat(arrayfun(@(Idx) Array1(Idx,1) + (0:Array1(Idx,3)-1).'*Array1(Idx,2), (1:size(Array1,1)).','uniform', 0))

Array2 = 7×1

10 13 16 1000 1178 1356 1534

[Gabriel Stanley]

Kinda disappointed this hasn't ended up being significantly faster in my use-case, but thank you for providing an answer. I never would've thought to use arrayfun (or cellfun & the like) because I've gotten the impression they're generally slower than a loop.

[Walter Roberson]

You didn't ask for performance, you asked for not using a loop. For most operations (but not all, not if you know the right obscure forms), arrayfun and cellfun are slower than looping.

If you were looking for performance, then your existing code could be tweeked to take advantage of cumsum() instead of calculating the indices each time, and you could use the calculation I used instead of using [original, colon expression] list constructor.

Answer 2

[Kevin Holly]

Array1 = [10,3,3;1000,178,4];
Array2 = cumsum(Array1,2)

Array2 = 2×3

10 13 16 1000 1178 1182

[Walter Roberson]

Tthe third column is the number of elements to generate, with the difference being the second column, and the starting point being the first column.

[Kevin Holly]

ah, thanks for pointing that out.