MATLAB: How to populate csv rows, rather than columns? This program creates a csv file with each vectorized image in a column, but i want to know if it’s possible to store each vectorized image as a row instead.

.csv filecsv

myDir = 'imgs2';
f = fullfile(myDir, '*.jpg'); % Change to whatever pattern you need.
theFiles = dir(f);
vector_imag = zeros(28^2, length(theFiles ));
for k = 1 : length(theFiles)
  baseFileName = theFiles(k).name;
  fullFileName = fullfile(myDir, baseFileName);
  fprintf(1, 'Now reading %s\n', fullFileName);
  imag = imread(fullFileName); %reads image
  imag_gray = rgb2gray(imag); %turns image to grayscale
  imag_28 = imresize(imag_gray, [28 28]); %resizes image
  vector_imag(:,k) = imag_28(:); %vectorizes the image
end
csvwrite('imgdata.csv', vector_imag); %writes vectorized image to csv file

Best Answer

It seems trivial to resolve to me:

Either tranpose your matrix when you write it:

csvwrite('imgdata.csv', vector_imag');

Or store the images in the rows of your matrix instead of the columns:

vector_imag = zeros(length(theFiles), 28^2);
for k = 1 : length(theFiles)
    %...
    vector_imag(k,:) = imag_28(:); %vectorizes the image
end
csvwrite('imgdata.csv', vector_imag);

Related Solutions

MATLAB: How to populate a csv file in a loop without overwriting it? I want to place each vector in a single row on each iteration. But the solution overwrites and creates a new csv each iteration.

Inside The Loop Don't Write To File And Populate A Matrix Instead.

vector_imag(:,k) = imag_28(:);

Then Write Everything To The File After The Loop

You will Have Better Performance As Well

Don't Forget To Preallocate Matrix Before Loop:

vector_imag = zeros(28^2, length(theFiles));

MATLAB: Is there any reason why this loop is not reading the images in order? I noticed that once it starts running, it reads the images in a random order. It prints the image being read on each itereation, and i dont know why it does not start at image 1.

dir() does not sort the returned information . It uses the order of entries returned by the operating system . In turn the operating system delegates to filesystem code. Different filesystemss have different sorting rules .

Some filesystems are defined as sorting directories as most recently used first out of the complete directory . Other filesystems divide the directory into blocks and rewrite one block at a time according to most recently used within the block . Others use binary tree representations .

MS Windows NTFS does not appear to formally define the sorting order . However in practice it appears to sort according to the utf16 non-canonical Unicode representation of the filenames . Apple's HFS+ is defined to sort according to utf16 representation of canonical Unicode .

Now one aspect of sorting according to complete filename including extension is that period sorts before the digits. That means that AA1.csv sorts before AA10.csv but it also means that AA10.csv sorts before AA2.csv . Files do not sort in the order 1 2 3 4 5 6 7 8 9 10 11 12 and so on: they sort in the order 1 10 11 12 ... 19 2 21 ... 29 3 30 31 ... 39.

That is probably what you are observing : they probably are in sorted order but the sorting is by characters not dictionary order . Likewise Spanish LL will not sort immediately after L as is defined for Spanish dictionary order .

You might want to look in the file exchange for natsort routines .

Best Answer

Related Solutions

MATLAB: How to populate a csv file in a loop without overwriting it? I want to place each vector in a single row on each iteration. But the solution overwrites and creates a new csv each iteration.

MATLAB: Is there any reason why this loop is not reading the images in order? I noticed that once it starts running, it reads the images in a random order. It prints the image being read on each itereation, and i dont know why it does not start at image 1.

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