How to extract data by looping through struct

Hi - I have some data saved as .mat files and i am trying to load it in (think I have done this) and then loop through the data in the struct to plot it all on the same graph (to then plot the mean average also.) Here is my script that doesn't work:

S = dir(fullfile(outputDir,'*.mat')); 
fields = fieldnames(S)
for k = 1:length(fields)
    F = fullfile(outputDir,S(k).name);
    S(k).data = load(F);
    S.(fields{k});
    %a = table2array(readtable(strcat(S(outputFolders).folder,'/', S(outputFolders).name)));
    
    for j= 1:length(S.data);
        %for i = 1:length(preSumTypesoutput)
        plot([-6 -5 -4 -3 -2 -1], data(:,i)); hold on;
        xticks([-6 -5 -4 -3 -2 -1])
        ylim([0 10])
        ylim([0 5])
        title('Pre-arousal vocalisations')
    end
    
end

and I attach some example data (I am trying to plot 6 of these).

Answer 1

[Walter Roberson]

S = dir(fullfile(outputDir,'*.mat')); 

S is the output of dir()

fields = fieldnames(S)

The field names returned by dir() include such items as 'name', 'folder', 'bytes', 'isdir' and so on.

for k = 1:length(fields)

You want to loop over the directory structure... unusual, but maybe there is a reason

    F = fullfile(outputDir,S(k).name);

You are using the field name index for the directory structure, and using it to index the struct array returned by dir() . If you wanted to loop over the fields of S you would need to use something like

    thisfield = {S.(fields{K})};

[Walter Roberson]

I recommend that you read http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

[Walter Roberson]

S = dir(fullfile(outputDir,'*.mat'));
filenames = fullfile({S.folder}, {S.name});
num_files = length(filenames);

tiledlayout('flow');

for K = 1 : num_files
    thisfile = filenames{K};
    [~, basename, ~] = fileparts(thisfile);
    datastruct = load(thisfile);
    data = datastruct.preSumTypesoutput;   %fixed field name!!
    nexttile();
    plot([-6 -5 -4 -3 -2 -1], data);
    xticks([-6 -5 -4 -3 -2 -1])
    ylim([0 10])
    ylim([0 5])
    title("Pre-arousal vocalisations for " + basename)
end

[Emu]

I see :) thank you so much that is incredibly helpful ! how would I plot a mean average?

Answer 2

[Emu]

ok thank you, but I still don't understand how to loop through my data to plot it..?