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 2018-2-4

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评论： Walter Roberson 2018-2-7

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.

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Walter Roberson 2018-2-4

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[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);

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HT 2018-2-7

Thanks.

Is it possible also to calculate other values, lets say mean of the cells in this code. And for specifying the threshold (variances<some value), is it possible to give control to user for specifying the value.

Walter Roberson 2018-2-7

在 MATLAB Online 中打开

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);