Answers.Body: <p>You're looking for a <a href="https://en.wikipedia.org/wiki/Heat_map" rel="nofollow noreferrer">heatmap</a>. Check out e.g. <a href="https://stackoverflow.com/q/33282368/3924118">https://stackoverflow.com/q/33282368/3924118</a> (if you like Python more than the others). See also <a href="https://seaborn.pydata.org/generated/seaborn.heatmap.html" rel="nofollow noreferrer">this documentation</a>.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-05-19T22:46:45.390Z
Answers.LastActivityDate: 2019-05-20T14:02:52.760Z
Answers.LastEditDate: 2019-05-20T14:02:52.760Z
Answers.UserDisplayName: nbro
Answers.Body: <p>I did it!</p>
  
  <pre><code>A = importdata('u.data');
  user_id = A(:, 1);
  movie_id = A(:, 2);
  rating = A(:, 3);
  
  % Build matrix R and w (weights matrix)
  R = zeros(943, 1682);
  w = zeros(943, 1682);
  for i=1:100000
      R(user_id(i), movie_id(i)) = rating(i);
      w(user_id(i), movie_id(i)) = 1;
  end
  
  
  m = HeatMap(R)
  ax = hm.plot; % 'ax' will be a handle to a standard MATLAB axes.
  colorbar('Peer', ax); % Turn the colorbar on
  caxis(ax, [0 5]); % Adjust the color limits
  </code></pre>
  
  <p>Output:</p>
  
  <p><a href="https://i.sstatic.net/qn3yn.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/qn3yn.png" alt="enter image description here"></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-05-20T03:34:29.500Z
Answers.LastActivityDate: 2019-05-20T03:34:29.500Z
Answers.UserDisplayName: NaveganTeX
Body: <p>I have a <code>.csv</code> file called <code>ratings.csv</code> with the following structure:</p>
  
  <pre><code>userID, movieID, rating
  3,      12,      5
  2,      7,       6
  </code></pre>
  
  <p>The rating scale goes from 0 to 5 stars. I want to be able to plot the sparsity of the matrix like it's done in the following picture: </p>
  
  <p><a href="https://i.sstatic.net/jtSLT.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/jtSLT.jpg" alt="pictiure"></a></p>
  
  <p>As you can see, ratings scale goes from 0 to 5 on the right. It is a very well thought plot. </p>
  
  <p>I have Matlab, Python, R etc. Could you come up with something and help me? I’ve tried hard but I cannot find the way to do it.</p>
  
Tags: <machine-learning><recommender-system><data-visualization>
Title: How do I plot a matrix of ratings?
UserDisplayName: NaveganTeX
ThreadText: # How do I plot a matrix of ratings?
  
  (Asked by: username_0 on 2019-05-19)
  
  I have a .csv file called ratings.csv with the following structure:
  userID, movieID, rating
  3,      12,      5
  2,      7,       6
  
  The rating scale goes from 0 to 5 stars. I want to be able to plot the sparsity of the matrix like it's done in the following picture: 
  
  As you can see, ratings scale goes from 0 to 5 on the right. It is a very well thought plot. 
  I have Matlab, Python, R etc. Could you come up with something and help me? I’ve tried hard but I cannot find the way to do it.
  
  **Tags:** machine-learning, recommender-system, data-visualization
  
  ---
  
  ## 2 answers
  
  ### Answer by username_1 on 2019-05-19. Score: 2
  
  You're looking for a [heatmap](https://en.wikipedia.org/wiki/Heat_map). Check out e.g. <https://stackoverflow.com/q/33282368/3924118> (if you like Python more than the others). See also [this documentation](https://seaborn.pydata.org/generated/seaborn.heatmap.html).
  
  
  ---
  
  ### Answer by username_0 on 2019-05-20. Score: 1
  
  I did it!
  A = importdata('u.data');
  user_id = A(:, 1);
  movie_id = A(:, 2);
  rating = A(:, 3);
  
  % Build matrix R and w (weights matrix)
  R = zeros(943, 1682);
  w = zeros(943, 1682);
  for i=1:100000
      R(user_id(i), movie_id(i)) = rating(i);
      w(user_id(i), movie_id(i)) = 1;
  end
  
  
  m = HeatMap(R)
  ax = hm.plot; % 'ax' will be a handle to a standard MATLAB axes.
  colorbar('Peer', ax); % Turn the colorbar on
  caxis(ax, [0 5]); % Adjust the color limits
  
  Output:
  
  
  ---
  
  