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Function to load a .mat file (which can be inside or outside matlab folder) and perform analysis for finding constant or near-zero variance values

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HT
HT on 4 Feb 2018
Commented: Walter Roberson on 7 Feb 2018
I have a matlab data file that has only one variable of type 1x1 struct which has 1x680 cell which has 680 MxN double values (values can be -ve, 0 or +ve). I want to load this data file using a function and find constant and near-zero variance values in this data set.
Thanks in advance.

Accepted Answer

Walter Roberson
Walter Roberson on 4 Feb 2018
[filename, pathname] = uigetfile('*.mat', 'Selected mat file');
if isnumeric(filename); return; end %user cancel
filename = fullfile(pathname, filename);
datastruct = load(filename);
varnames = fieldnames(datastruct);
datacell = datastruct.(varnames{1}); %there should only _be_ one, but just in case there are more
variances = cellfun(@(M) var(M(:)), datacell);
has_small_variance = abs(variances) < 1e-5;
selected_cells = datacell(has_small_variance);
  7 Comments
Walter Roberson
Walter Roberson on 7 Feb 2018
tol = input('What tolerance do you want?');
means = cellfun(@mean2, datacell);
variances = cellfun(@(M) var(M(:)), datacell);
has_small_variance = abs(variances) < tol;
selected_cells = datacell(has_small_variance);
selected_variances = variances(has_small_variance);
selected_means = means(has_small_variance);

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