Create a list of images from subfolders with specific names using dir , strcat!

There should be two seperate for-loop but in the first loop it overwright and just I can get the last year images. I also tried fullfile but I got problem with the imread in the second loop because of the path name. I want to create a list of all images with special names as what assgined below among the total number located in diffrent subfolder. But It just gives the last years.

%activity= 'run' or 'dart'
year1 = 1980
year2= 2010
for num= year1:year2 
        switch activity 
            case 'Indai'  
            path = ['C\folder\competition\run','\',num2str(num),'\']; % get images with this name from all subfolders 
            if strcmp(age,'rd')                     
                ag = 'old';
                list_images= dir([datapath 'run_',num2str(d),'*_',country,ag,'.png'])
            elseif strcmp(age,'rs')                    %German
                ag = '';
                list_images=dir([path 'run_',num2str(d),'*_',country,ag,'.png']);% get images with this name from all subfolders 
            end
            ti = 1;
        case 'Africa'
                path = ['C\folder\competition\dart','\',num2str(num),'\'];            
                list_images=dir([datapath 'dart',country,'_',num2str(d),'*.png'])% get images with this name from all subfolders 
            ti = 2;
end

 for i=1:length(images)
           filename = strcat(images(i).folder,'/',images(i).name);% Concatenate strings horizontally to create a full path
           I= imread(filename);% fo further process of showing image a series 
 end

Answer 1

[Guillaume]

Very confusing code and confusing question.

But It just gives the last years.

Well, yes of course, in the loop you overwrite list_images at each step. So when the loop finishes, you're left with just the value you've written last.

You could rewrite your loop as such:

year1 = 1980
year2 = 2010
years = year1:year2;
list_images = cell(size(years));
for yearindex = 1:numel(years)
    num = years(yearindex);   %num is an extremely poor variable name!
    %....
        list_images{yearindex} = ...  
 end

But the whole thing should be rewritten to extract the switch and the if...elseif out of the loop, and using fullfile indeed instead of char vector concatenation. fullfile is always more reliable and if you've got problem (what problem? always state the full text of any error you get), then it's because you've made a mistake, not because it doesn't work.

[vania todorova]

newbie here. why does it have to be specifically a cell array ? is it something that works with images better? i m mostly a python user and i would just use a list but trying to figure out how to separate image ds into groups of 5 images easiest . thanks!

[FSh]

In my experince, Guillaume might know better!

Surely there can be multiple solutions to a problem and if that works for you, there should be no issue.

In my case I had multiple folders (..., 2018, 2019, 2020, ...) in my main directory and I wanted to run the process for only 2 different years each time. So a simple dir could not help in this case!!!!

But I also experienced that if there are inconsistencies in array size, cell is the best solution.

So I used this;

list_images2 = struct('name',{},'folder',{},'date',{},'bytes',{},'isdir',{},'datenum',{});
list_images = struct('name',{},'folder',{},'date',{},'bytes',{},'isdir',{},'datenum',{});
   
for yearindex = Y1:Y2
    datapath = [main_path,'sample' ,'/',num2str(yearindex),'/'];
    list_images = dir([datapath 'image_',num2str(yearindex),'*_*.tif']);
    list_images= list_images(:,1);
    list_images2 = [list_images2;list_images];
end