Function 'subsindex' is not defined for values of class 'cell'.

Hi,

I understand what error says but I don't know how to improve my function. I am not sure what exactly is seen as cell and how to achieve my goal. I loaded file to be read.

*Error using subsindex Function 'subsindex' is not defined for values of class 'cell'.

Error in EEGmeans (line 36) means(i) = mean(alldata(n,:));*

function [ means ] = EEGmeans( )
  %EEGmeans loads the .mat file with EEG signal and calculates means for
  %electrode and trials determined by user

    %loading .mat file
    load('eeg_data.mat');

    %user determines number of elecrode and trials
    for h=1:64
    disp([num2str(h), ' - ', data_org.label{h}])
    end
    eprompt = 'Type number of electrode. You can see displayed numbers and labels in your command window.';
    tprompt = 'Type numbers of trials (1-61) in form of a vector [t1, t2, t3, ...].';
    edlg_title = 'Electrode';
    tdlg_title = 'Trials';
    num_lines = 1;
    defe = {'1'};
    deft = {'[1, 2, 3]'};
    electrode = str2double((inputdlg(eprompt,edlg_title,num_lines,defe)));
    trials = (inputdlg(tprompt,tdlg_title,num_lines,deft));

    alldata = zeros(61,160);

    %getting data for trials for selected electrode
    for g = 1 : 61
            alldata(g,:)=data_org.trial{g}(electrode,:);
    end

    %calculating means
    means = zeros(1, length(trials));

    for i = 1 : length(trials)
        n = trials(i);
        means(i) = mean(alldata(n,:));
    end

    %displaying results
    msgbox('Operation Completed. Arithmetic means for given electrode and trials are as follows: ', 'Success','custom', means);

    end

Answer 1

[Sean de Wolski]

trials is a cell array or a container, when you create n, n is a cell and you cannot index with a cell:

c = {1}
c = 
  [1]
>> x = magic(3)
x =
   8     1     6
   3     5     7
   4     9     2
>> x(c,2)
Error using subsindex
Function 'subsindex' is not defined for values of class 'cell'.

You likely need to use {} to extract the n from trials:

n = trials{i}

This extracts the contents of the cell into n rather than the cell itself. For my simple example:

x(c{1},2)

[Katarzyna Wieciorek]

Thank you very much. New error:

Index exceeds matrix dimensions.

Error in EEGmeans (line 36) means(i) = mean(alldata(n,:));

What should I do now? trials were as default, [1, 2, 3] so it shouldn't exceed anything.

[Sean de Wolski]

run each little piece of the code until you figure out what's causing the error. Does trials have three rows?

[Katarzyna Wieciorek]

I got rid of comas in trials, so it is ex. [1 2 3]

Problem stays in this loop:

for i = 1 : length(trials)
    n = str2num(trials{i});
    means(i) = mean(alldata(n,:));
end

In an assignment A(I) = B, the number of elements in B and I must be the same.

Error in EEGmeans (line 36) means(i) = mean(alldata(n,:));

[Sean de Wolski]

The commas aren't the problem

trials= [1 2 3]
for i = 1 : length(trials)
  means(i) = mean(alldata(trials(i),:));
end

[Katarzyna Wieciorek]

trials are supposed to be typed by user in dialog box and then they are cell (this is how inputdlg works), so for your solution:

Error using subsindex
Function 'subsindex' is not defined for values of class 'cell'.

Error in EEGmeans (line 35)
    means(i) = mean(alldata(trials(i),:));

when I do trials{i}:

Index exceeds matrix dimensions.

Error in EEGmeans (line 35)
    means(i) = mean(alldata(trials{i},:));