I AM NOT UNDERSTANDING THE ERROR THIS IS MY CODE ERROR:-Error using horzcat Dimensions of matrices being concatenated are not consistent. Error in personIden​tifierImag​eReader (line 21) image_data1 = [image_data1, last_image];

clear all
close all

% Training Data
% Train File
chosen_folder = 'C:\Users\123\Music\face-recognition-master\pic';
filename_list = dir(chosen_folder); %this allows us to read all filenames in a folder and save it in a structure

xtrain = [];
y = [];
% x1 = zeros(960, 624);
image_data1 = [];
N = length(filename_list); %the length of the filename structure
for n = 3:N
    filename = fullfile(chosen_folder,filename_list(n,1).name); %choosing the name of the last file

      last_image = imread(filename,'pgm'); %reading the last file
      image_data1 = [image_data1, last_image];

      %figure(1),image(last_image);colormap(gray) %drawing the image,just to understand image files

      [M N2 ] = size(last_image);
      new_x = reshape(last_image,M*N2,1);
      xtrain(:,n-2) = new_x;
      %figure(2),plot(new_x,'.');

      a = strfind(filename,'an2i');
      if a
          y(n-2) = .9;
      else
          y(n-2) = .1;
      end  
  end

[A B] = size(y);
randData = randperm(B);
yRand = y(:,randData);
xRand = xtrain(:,randData);

% % Test data
% % Test File
% chosen_folder = 'U:\private\Machine Learning\Neural Networks\ImageReader\All_Faces';
% filename_list = dir(chosen_folder); %this allows us to read all filenames in a folder and save it in a structure
% 
% realY = [];
% xtest = [];
% image_datatest = [];
% N = length(filename_list); %the length of the filename structure
% for n = 3:N
%     filename = fullfile(chosen_folder,filename_list(n,1).name); %choosing the name of the last file
%     
%     last_image = imread(filename,'pgm'); %reading the last file
%     image_datatest = [image_datatest, last_image];
%     
%     %figure(1),image(last_image);colormap(gray) %drawing the image,just to understand image files
%     
%     [M N ] = size(last_image);
%     new_x = reshape(last_image,M*N,1);
%     xtest = [xtest, new_x];
%     %figure(2),plot(new_x,'.');
%     
%      a = strfind(filename,'an2i');
%     if a
%         realY(n-2) = 1;
%     else
%         realY(n-2) = 0;
%     end
% end

[EDITED, Jan, Code formatted]

Answer 1

[Jan]

The error message means, that the dimensions of image_data1 and last_image do not match. For a horizontal concatenation the number of rows must be equal.

Use the debugger to check this, run this in the command window:

dbstop if error

Now run your code again. Matlab stops, when the error occurs. Then display the sizes of the arrays:

size(image_data1)
size(last_image)

[waqas siddiqui]

Subscripted assignment dimension mismatch.

Error in personIdentifierImageReader (line 25) xtrain(:,n-2) = new_x; even after the dimensions of images are same; the above error is resolved

Answer 2

[Andreas Krahnke]

The problem are inconsistent sizes of the matrices you are training to put together. First, you initialize

image_data1 = [];

to be a 0x0 matrix. Then you try to combine it with the newly imported image, which has most likely a different number of rows

image_data1 = [image_data1, last_image];

Since horzcat is the function behind [a,b], the error message means that you cannot put a matrix with 0 rows in front of a matrix with a non-zero number of rows.

If all images have the same number of rows, you should load the first image before the loop to initialize image_data1. Alternatively, you could load the images into a 3D array. Since you seem to know the number of images ahead of time, you could preallocate the array before the loop to save time.

[waqas siddiqui]

this is not working

Answer 3

[Tobias Kumie]

Dear All,

I have a column matric A of 35040 x 6 and B of 17514 x 6

However when I run it, matlab gives me an error as quoted hereunder;

"Error using horzcat

Dimensions of arrays being concatenated are not consistent".

How can I make both matrix consistent to perform arithmetic operations in matlab?

Thanks

Tobias