MATLAB: Run the same code with multiple variables.

for looploopmatrix

Hi!

I have 10-20 different matrices, each containing a set of coordinates (one longitude column & one latitude column). I wrote a code to calculate stuff for one matrix, but I want to loop the whole code for all of my matrices.

I need to compare the results from each matrix, so their results have to end up in a joint new matrix.

Thank you!

Best Answer

It might be convenient to store each of the 10-20 matrices as one cell in a cell array, since that doesn't require that they have the same size. Then, for each cell, call the code to process the one array in that cell.

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MATLAB: How to do leave-one-out cross validation of samples in cells

C = num2cell(1:50);

Method One: Colon Operator

N = numel(C);
for k = 1:N
    ind = C{k}
    tmp = vertcat(C{[1:N-1,N+1:end]})
end

Method Two: setdiff

vec = 1:numel(C);
for k = vec
    ind = C{k}
    tmp = vertcat(C{setdiff(vec,k)})
end

MATLAB: Concatenate arrays within a loop,

Easy, given any number of arrays in a cell array C. You could use a loop like this, although it is inefficient because the output array is not preallocated:

C = {[1,2],[3,4],...} % cell array of arrays.
A = C{1};
for k = 2:numel(C)
    A = [A;C{k}];
end

Simpler and more efficient would be to concatenate them all at once, without a loop, e.g.:

A = vertcat(C{:})

Whatever you do, do NOT try to access variable names dynamically in a loop! Read this to know why:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

Using an array (e.g. a cell array) and indexing is much simpler, neater, much more efficient, less buggy, and easier to debug.

Best Answer

Related Solutions

MATLAB: How to do leave-one-out cross validation of samples in cells

MATLAB: Concatenate arrays within a loop,

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