summing every twelve files from multiple .mat files

Hi everyone,

 I am new to Matlab. This may look trivial.  I have thousands .mat matrix files of size K(180, 360). I want to do two things:

1. Read these files and summing every twelve files
2. Clip the result from size (180, 360) to something like (100,100)
3. save the results

This is what I have done:

dirname = uigetdir;
Files = dir(fullfile(dirname,'*.mat'));
Total = zeros(180,360);
N=length(Files);
for k=1:N 
   ppm.Frame=load(Files(k).name)); % read the files
   while k<= 12; 
     Total = Total + pp.Frame % do the summing of first twelve files here
     k = k+1;
   else 
     k=0;
     % How do I resize the result here?
     save(Total)
     clear Total 
  end

Help would be highly appreciated.

[Jan]

What exactly is "K(180, 360)"? How can files be added? Do you mean that the MAT-files contain a variables called "K", which has the size [180 x 360]? And you want to create the sum over these values? How is "every 12 files" defined? In alphabetical order? How should the clipping be applied exatcly? Do you want to remove the right, left, upper, lower rows and columns?

Answer 1

[Jan]

I've formatted your code properly. As soon as you do so, you can see, that there cannot be an else ibn a while loop. The for loop counter k should not be modified inside the loop - you will see a corresponding warning in the editor.

The code contains more problems, e.g. you read the file into "ppm.Frame", but try to access ""pp.Frame". I guess, you want something similar to this:

dirname = uigetdir;
Files = dir(fullfile(dirname,'*.mat'));

N     = length(Files);
count = 0;
for iFile = 1:N 
   if count == 0
      Total = zeros(180,360);
   end
   count = count + 1;

     FileData = load(fullfile(dirname, Files(iFile).name)); % read the files
     Total    = Total + FileData.Frame;
     count    = count + 1;

     if count == 12
       % It is unclear how you want to "clip" Total.
       Total = ??? Perhaps resize()
       % Or: Total = Total(1:100, 1:100, :);
       save(Total)
       count = 0;
     end
  end

[FeAde]

Hi Jan, Thanks s much for your response:

Actually the files are 30min precipitation values represented in a matrix. Want to accumulate them to 6 hr (therefore 12 variable in a file). The global coverage of K(180,360) where this is Y and X (long and lat).

The date is like this:

2011060100000, 2011060100300, 2011060101000, .

. . etc

where

This is Year:MM:dd:hrhr:minminmin

The files are in ascending order in the folder. I hope the function would pick each file(s) (i.e. first 12) to be the first 12 in the folder? Or is there a way to call the date as a step or sequentially?

can I do something like this for clipping to get(Total(100,100):

Total(80:end,:)=[]; Total(:,260:end)=[]; Total(:,1:80)=[];

save(Total)

Thanks a lot!!!