Error "Undefined function or variable"

I am receiving one of the following error messages. How can I resolve this issue?

Undefined function or variable 'segment_list'.

Code:

labels = {'cheduepalle';'fame';'chevuoi';'basta'};

segment_counter = 1;
for data_counter=1:num_of_samples
    currVideo = data_files(data_counter).Video;
    for label_counter = 1: length(currVideo.Labels)
        if ismember(currVideo.Labels(label_counter).Name, labels)
            s = struct('videoID', data_counter, 'start',currVideo.Labels(label_counter).Begin, 'end', currVideo.Labels(label_counter).End, 'label', currVideo.Labels(label_counter).Name);
            segment_list(segment_counter) = s;
            segment_counter = segment_counter + 1;
        end
    end
end

[Cris LaPierre]

I don't believe you have shared the line of code that is causing the error. Please copy the complete error essage (all the red text) and paste that here.

[PaunBGD]

Undefined function or variable 'segment_list'.

Error in main (line 287)

for idx = 1:length(segment_list)

Here is the code, starting from line 287:

for idx = 1:length(segment_list)
    curr_face = [];
    curr_lhand = [];
    curr_rhand = [];
    for Frameidx = segment_list(idx).start:segment_list(idx).end
        curr_face = [curr_face; data_files(segment_list(idx).videoID).Video.Frames(Frameidx).Skeleton.PixelPosition(4,:)];
        curr_lhand = [curr_lhand; data_files(segment_list(idx).videoID).Video.Frames(Frameidx).Skeleton.PixelPosition(8,:)];
        curr_rhand = [curr_rhand; data_files(segment_list(idx).videoID).Video.Frames(Frameidx).Skeleton.PixelPosition(12,:)];
    end
    segment_list(idx).FaceArray = curr_face;
    segment_list(idx).lHandArray = curr_lhand;
    segment_list(idx).rHandArray = curr_rhand;
end

[Cris LaPierre]

It looks like segment_list never gets created. This could be because your for loops never end up running, or because your if conditional is never true. See Walter's reply below for more details.

Answer 1

[Walter Roberson]

Perhaps num_of_samples is less than 1.

Perhaps data_files(data_counter).Video is empty for all num_of_samples different videos.

Perhaps none of the labels on any of the videos exactly match any of the values in the variable labels

[Walter Roberson]

Right after you assign to the variable labels do

segment_list = struct('videoID', [], 'start', [], 'end', [], 'label', []);

This will initialize segment_list to an empty structure with the required fields.

Then if any of the "Perhaps" that I listed above hold true, then at least segment_list will be defined.

[PaunBGD]

Problem solved. Thank you so much!