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How do I animate this line plot?

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I am trying to make an animated line plot changing based on the number of water molecules at a given amino acid inside an ion channel. I have some initial code to do this. The plot is created the way I want for the most part, but I'm not sure what to do with the for loop part. Because the x-data is just the residue (# of waters vs Residue), so the x-data doesn't change, but a line needs a y-coordinate and an x-coordinate. An example of the plot and the matrix is attached, which is a plot from just the first row of # of water molecules in the 1667 x 4 matrix, as well as the modified code so far. At each of those 4 residues, the # number of waters is changing each frame, but I didn't want to plot just moving points, but an animated line of the # of waters changing. A line like the plot in the .xls attached file.

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Kelly McGuire
Kelly McGuire on 30 Apr 2018
Updated code. It is now plotting the first row of data in the matrix, but stops at the second row with the error: "Value must be a vector of numeric type". Error in line 34 l.XData(i,j) = xData(i,j);

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Accepted Answer

Ameer Hamza
Ameer Hamza on 30 Apr 2018
The following code will generate the moving animated line as you described in the question,
data = xlsread('WaterPerResidueMatrix.xls', 1);
animationWriter = VideoWriter('HSPtoHSPCircle');
stepsBetweenTwoLines = 10;
l = line();
l.XData = 1:4;
l.YData = [];
ax = gca;
ax.XLim = [1 4];
ax.XTick = 1:4;
ax.XTickLabel = {'residue 1', 'residue 2', 'residue 3', 'residue 4'};
t = linspace(0, 1, stepsBetweenTwoLines);
for i = 1:size(data, 1)-1
% create data for circle plot or any other
% processing you want to do
line1 = data(i, :)';
line2 = data(i+1, :)';
line = line1*(1-t) + line2*t;
for j = line
l.YData = j;
frame = getframe(gcf);
writeVideo(animationWriter, frame);
Here is the output obtained from this on my PC.
As you can see I forgot to add YLim, therefore, the y-axis keep moving. Also, you can control speed by changing animation writer.FrameRate or the stepsBetweenTwoLines variable i defined above. Similarly, you can add other formatting options e.g. line thickness, color, etc.


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Ameer Hamza
Ameer Hamza on 30 Apr 2018
You just need to read documentation clearly. MATLAB has well-maintained documentation. Whenever you face a problem related to some function, just look at its documentation and you will find relevant information. Of course your ability to spot the relevant information increase with practice and experience.
Kelly McGuire
Kelly McGuire on 30 Apr 2018
I will work on that. The plot looks great. Would it be simple to add a control line to the plot, one that doesn't move during the animation, it's just the initial # of Waters Per Residue line from the initial structure that would be static on plot as a comparison to the line that is moving?
Ameer Hamza
Ameer Hamza on 1 May 2018
You can add at the beginning,
l2 = line();
l2.XData = 1:4;
l2.YData = data(1,:);
hold on
Before the lines for l in the beginning.

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