Bizarre issue: old file list recalled after using load()

Hi folks,

So I have some really simple code to load MATLAB files one by one, and write some data pulled from those files into a corresponding pre-existing file in Excel. I'm utterly flummoxed by what's happening in my code. Here is my code:

if true
  fileList = ls('*exp.mat')
[m n] = size(fileList)
for i = 1:m
  fileName = deblank(fileList(i,:));
  excelName = fileList(i,1:3);
  excelFile = strcat('F:\PhD\Pilot Studies\Reaching and Grasping\Excel Spreadsheets\', upper(excelName), '.xlsx');
  a = strfind(fileName, 'dom'); % find out what type of file it is
  b = strfind(fileName, 'nondom');
  c = strfind(fileName, 'binoc');

    if isempty(c) == 0; % if filename is binocular
        fileType = 1; % use filetype 1
    end
    if isempty(a) == 0; % if filename is for dominant eye
        fileType = 2; % use filetype 2
    end
    if isempty(b) == 0; % if filename is for nondominant eye
        fileType = 3; % use filetype 3
    end

    load(fileName);
    tempfile = [data(:,[1 2 3 7])]; % get the data we want
    if fileType == 1; % set target cell according to file type
        targetCell = 'D2:G59';
    end
    if fileType == 2;
        targetCell = 'D64:G121';
    end
    if fileType == 3;
        targetCell = 'D126:G183';
    end

    % initiate xlswrite1 code

    Excel = actxserver ('Excel.Application'); 
    File=excelFile; 
    if ~exist(File,'file') 
    ExcelWorkbook = Excel.workbooks.Add; 
    ExcelWorkbook.SaveAs(File,1); 
    ExcelWorkbook.Close(false); 
    end 
    invoke(Excel.Workbooks,'Open',File);

    xlswrite1(excelFile, tempfile, 1, targetCell); % write the MATLAB data to the specified cell in the spreadsheet

    % close the Excel active server

    invoke(Excel.ActiveWorkbook,'Save'); 
    Excel.Quit 
    Excel.delete 
    clear Excel

    end

end

Works fine as an individual code block outside of loop, but I put it in a loop because I might be using it again in the future for other files. Soooo. The contents of my fileList variable are supposed to be as follows:

if true
  ajs_141113_binoc_block2_exp.mat      
ajs_141113_domleft_block1_exp.mat    
ajs_141113_nondomright_block3_exp.mat
cmb_080713_binoc_block1_exp.mat      
cmb_080713_domright_block2_exp.mat   
cmb_080713_nondomleft_block3_exp.mat 
eom_081113_binoc_block3_exp.mat      
eom_121113_domright_block2_exp.mat   
eom_121113_nondomleft_block1_exp.mat 
mep_040613_binoc_exp.mat             
mep_040613_domleft_exp.mat           
mep_040613_nomdomright_exp.mat       
mrj_270613_binoc_block2_exp.mat      
mrj_270613_domright_block3_exp.mat   
mrj_270613_nondomleft_block1_exp.mat 
noj_040713_binoc_block2_exp.mat      
noj_040713_domleft_block1_exp.mat    
noj_040713_nondomright_block3_exp.mat
saa_111113_binoc_block2_exp.mat      
saa_111113_domright_block3_exp.mat   
saa_111113_nondomleft_block1_exp.mat 
sjs_131113_binoc_block3_exp.mat      
sjs_131113_domleft_block2_exp.mat    
sjs_131113_nondomright_block1_exp.mat
stt_260913_binoc_block1_exp.mat      
stt_260913_domright_block3_exp.mat   
stt_260913_nondomleft_block2_exp.mat 
tec_040713_binoc_block3_exp.mat      
tec_040713_domright_block1_exp.mat   
tec_040713_nondomleft_block2_exp.mat 

end

If you step through my code, it stays like that right up until executing load(fileName) - after executing that, the fileList changes to...

if true
  TEC_040713_domright_block1_exp.mat   
air_260613_binoc_block3_exp.mat      
air_260613_domright_exp.mat          
air_260613_nondomleft_block1_exp.mat 
as_141113_binoc_block2_exp.mat       
as_141113_domleft_block1_exp.mat     
as_141113_nondomright_block3_exp.mat 
cmb_080713_binoc_block1_exp.mat      
cmb_080713_domright_block2_exp.mat   
cmb_080713_nondomleft_block3_exp.mat 
em_081113_binoc_block3_exp.mat       
em_121113_domright_block2_exp.mat    
em_121113_nondomleft_block1_exp.mat  
mefp_040613_bin_exp.mat              
mefp_040613_mon_l_exp.mat            
mefp_040613_mon_r_exp.mat            
mrj_270613_binoc_block2_exp.mat      
mrj_270613_domright_block3_exp.mat   
mrj_270613_nondomleft_block1_exp.mat 
noj_040713_binoc_block2_exp.mat      
noj_040713_domleft_block1_exp.mat    
noj_040713_nondomright_block3_exp.mat
saa_111113_binoc_block2_exp.mat      
saa_111113_domright_block3_exp.mat   
saa_111113_nondomleft_block1_exp.mat 
ss_131113_binoc_block3_exp.mat       
ss_131113_domleft_block2_exp.mat     
ss_131113_nondomright_block1_exp.mat 
stt_260913_binoc_block1_exp.mat      
stt_260913_domright_block3_exp.mat   
stt_260913_nondomleft_block2_exp.mat 
tec_040713_binoc_block3_exp.mat      
tec_040713_nondomleft_block2_exp.mat 

end

See the capitalised TEC at the top? And that extra subject with initials air? And how the subject initials are sometimes only two letters long? I changed all of these things a day ago. So why is my use of the load function calling up an obsolete list of files that last existed a day ago, when I haven't even called ls as part of the load function, never mind assigning it the variable fileList? It also messes up my code loop as on the 2nd iteration it's trying to load a file that no longer exists, due to using this obsolete file list. If I run fileName = ls('*exp.mat') again, the proper file list comes up, that doesn't have the extra subject and the capitalised TEC.

I mean, it's not a big deal, I can just move the generation of fileList inside the loop and remake the list every time. I'm just really bemused as to why calling load() not only alters my other completely unrelated variable, but also uses a legacy list of files from a day ago that doesn't exist when you call ls() now. I used inmem to see what MATLAB was holding in memory and cleared ls as a result but it made no difference. Does anyone have any explanation?

Thanks!

[Walter Roberson]

Make sure that you have closed all files before you begin.

If you are writing to .m files that are in use, then you need to "clear" the function name before the changed version becomes usable in that MATLAB session.

[Marianne]

As an update, I encountered this problem again with another piece of code doing a similar kind of activity. I again had to move the list generation inside the loop, otherwise it substituted a random filelist from a completely different folder! I also got this error when using the line of code calling the load() function: Warning: Interface.000208DA_0000_0000_C000_000000000046 object could not be loaded.

Answer 1

[Jan]

Calling load() without catching the output has such side-effects, when a variable stored inside the MAT-file overwrites a locally used variable from the code:

a = 1;
data = rand(5);
save('test.mat');

a = 17;
load('test.mat');
disp(a)   %  1 !!!

Therefore it is a good programming pattern to catch the output:

FileData = load(fileName);
tempfile = [FileData.data(:,[1 2 3 7])];

Using ls('*exp.mat') to get a list of file names is very indirect. because it converts the output of dir to a CHAR-Matrix padded with spaces. Better:

fileDir  = dir(*exp.mat');
fileName = {fileDir.name};