CODEWITHSUNDEEP
arraysmatlabmultidimensional-array
Toygan
Toygan

Reputation: 422

MATLAB: Linear Indexing Multidimensions

I'm trying to assign some values to a matrix.In the case of 2 or 3 dimension, it is easy to use sub2ind. However the data I use has 23 dimensions. The situation could be explained better with an example. A is a matrix which has 3x4x5x6x7dimensions. I want to assign something to A(1,2,3,4,5) with linear indexing. Normally, it is possible with sub2ind like:

A(sub2ind(siz,1,2,3,4,5)) = any_var;

However the thing I want is that assigning the sub2ind input with an array instead of commas. Is there anything which satisfies this in MATLAB? 

A(sub2ind(siz,[1 2 3 4 5])) = any_var; % I want something like this.

Upvotes: 2

Views: 125

Answers (1)

Luis Mendo
Luis Mendo

Reputation: 112679

Define the vector with the index values

x = [1 2 3 4 5];

Then you can convert to cell (using num2cell) and from that to a comma-separated list:

xc = num2cell(x);
A(sub2ind(siz, xc{:})) = any_var;

Or you could do the computation directly and avoid sub2ind. To convert to linear index, subtract 1 from the index along the k-th dimension and multiply by the cumulative product of the sizes of the preceding dimensions. The sum for all k plus 1 is the linear index:

A(x(1) + sum((x(2:end)-1).*cumprod(siz(1:end-1)))) = any_var;

Upvotes: 5

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