Doubles Output in Matrix?

New to Matlab so please forgive me. I'm trying to create a matrix, mom, that updates with data from the 4th column of each file that's read:

myDir = uigetdir; 
my_mom_Files = dir(fullfile(myDir,'MRFbeam-Mom-*.txt')); 
mom = [];
for k = 1:length(my_mom_Files)
  baseFileName = my_mom_Files(k).name;
  fullFileName = fullfile(myDir, baseFileName);
  %fprintf(1, 'Now reading %s\n', fullFileName);
  mom_data = load(fullFileName);  
  mom_col  = mom_data(:, 4);
  mom = [mom; {mom_col}];
end

The output is as follows:

   { 6181×1 double}
    { 7849×1 double}
    { 3107×1 double}
    { 3107×1 double}
    { 2999×1 double}
    { 2999×1 double}
    { 2000×1 double}
    { 2000×1 double}
    { 2999×1 double}
    { 2999×1 double}
    { 4425×1 double}
    { 6181×1 double}
    { 4425×1 double}
    { 2499×1 double}
    { 2499×1 double}
    {11293×1 double}
    {11293×1 double}
    {29980×1 double}
    {29980×1 double}
    { 4825×1 double}
    { 4825×1 double}
    { 1123×1 double}
    { 1123×1 double}
    { 2225×1 double}
    { 2225×1 double}
    { 2221×1 double}
    { 2221×1 double}
    { 7849×1 double}

When I try cell2mat, the size of my matrix changes from 28 x 1 to in the thousands.

Ultimately I would like to print the value found for each file and store it in a matrix. My final goal is to plot these values.

TYIA

Answer 1

[Image Analyst]

Why are you making it a cell array? No need for that. Assuming all the columns are the same height, just stuff it into a column of a preallocated matrix:

myDir = uigetdir;
my_mom_Files = dir(fullfile(myDir,'MRFbeam-Mom-*.txt'));
numFiles = length(my_mom_Files)
numRows = 10; % Whatever -- it's the number of rows in mom_data.
mom4 = zeros(runRows, numFiles);
for k = 1 : numFiles
    baseFileName = my_mom_Files(k).name;
    fullFileName = fullfile(myDir, baseFileName);
    %fprintf(1, 'Now reading %s\n', fullFileName);
    mom_data = load(fullFileName);
    thisColumn4  = mom_data(:, 4);
    mom4(:, k) = thisColumn4;
end

[nogooduser]

Thanks! I tried running your code, here's the error it produced:

Unrecognized function or variable 'runRows'.

Error in IMKplot_0P05_test (line 5)
mom4 = zeros(runRows, numFiles);

[nogooduser]

If runRows was a typo and should be "numRows", and the code is run, here's the other error Matlab produces:

>> IMKplot_0P05_test
Unable to perform assignment because the size of the left side is 6181-by-1 and the size of the
right side is 7849-by-1.

Error in IMKplot_0P05_test (line 12)
    mom4(:, k) = thisColumn4;

[Image Analyst]

So you obviously have at least 7848 rows, not 6818. Try this:

myDir = uigetdir;
my_mom_Files = dir(fullfile(myDir,'MRFbeam-Mom-*.txt'));
numFiles = length(my_mom_Files)
numRows = 7849; % Whatever -- it's the number of rows in mom_data.
mom4 = zeros(numRows, numFiles);
for k = 1 : numFiles
    baseFileName = my_mom_Files(k).name;
    fullFileName = fullfile(myDir, baseFileName);
    %fprintf(1, 'Now reading %s\n', fullFileName);
    mom_data = load(fullFileName);
    thisColumn4  = mom_data(:, 4);
    mom4(1 : size(thisColumn4, 1), k) = thisColumn4;
end

[nogooduser]

Thanks for answering so fast! My data has different #s of rows which I wasn't expecting. I ran the code and at the end disp(mom4). The output was a matrix of zeros.

[Image Analyst]

Try this:

Debugging in MATLAB | Doug's MATLAB Video Tutorials

Then set a breakpoint and learn why thisColumn4 is all zeros. Or why numfiles is zero so the loop never gets entered.

[nogooduser]

Hi! Sorry for the delayed response. I plotted and your code works beautifully! Thank you so much for your help.