How to remove certain rows of data in a cell array using logical indexing?

Hi,

I have a 1x11 cell array and I am trying to clean the data using logical indexing, i.e. remove certain rows in each cell once a simple condition is met. The cells are of different lengths (but always 20 columns) and I want the same conditions to be applied to all, i.e. when certain parameters (representing a number of the columns in each cell) exceed a certain threshold.

What is the best way to approach this? Thus far, I have recevied the 'matrix index is out of range for deletion' error message.

Thanks

Daniel

Answer 1

[the cyclist]

Here is an example where I keep only rows of each matrix where the sum is greater than 1. Perhaps you can adapt it to your specific criterion:

% Set the random seed
rng default

% Create some input data
n = 11;
c_in = cell(1,n);
for ni = 1:n
    c_in{ni} = rand(7,2);
end

% Preallocate the output cell array to be the same size as the input
c_out = cell(size(c_in));

% For each cell, keep only the rows that sum to greater than 1
for ni = 1:n
    keepRowIndex = sum(c_in{ni},2) > 1;
    c_out{ni} = c_in{ni}(keepRowIndex,:);
end

There are slicker ways to do this, using the cellfun function, but better to understand this way first.

[the cyclist]

The equivalent method using cellfun:

c_out = cellfun(@(x)x(sum(x,2)>1,:),c_in,'UniformOutput',false);

This would take the place of the for loop over the cells, and you would also not need the preallocation step.

[Daniel Rowe]

Thank you