Plot data above current axis

I have a pseudocolor (contourf) plot that I want to add to in the margins around the plot. How do I place the plot the new data (just some lines) in the location shown in the circleed area in picture attached?

Answer 1

[Walter Roberson]

There are several possible ways to proceed:

• Create two different axes() specifying Position for each one, possibly using 'Units', 'normalized'. Use the same width and same xlim() for both of them -- consider using linkaxes . If you use this option, you can use whatever y coordinate range is easiest for each axes; OR
• use subplot or tiledlayout to create subplots. It is easier to control spacing with tiledlayout -- but you still might not be able to get them as close as you would like. If you use this option, you can use whatever y coordiante range is easiest for each axes; OR
• image() and imagesc() and pcolor() and contourf() by default use the matrix sizes to establish coordinates. You can take the y coordinates of the additional plot and scale them to have range proportionate to the array sizes, and then add the coordinate of the top of the array to all of the y values and then plot using that -- effectively using the same axes but positioning the data above the color area. This has the advantage of only using one axes, but has the disadvantage that axes labels and datatips will not match the actual y range unless you do a bunch of playing around.
• you could use yyaxis left and yyaxis right, but in order to position the other plot above the color area you need to do a bunch of playing with coordinate scales and ylim

[Anas Khan]

Ok, if I used either of those options, they would be associated with a mini plot, which has x and y axes and a background, right? The way I tried to do it is with hold on and plotting my vertical lines at the desired X coordinates of the contourf plot. I used the Y coordinates of the contourf plot to place the lines above the maximum Y value. But this just extended the Y axis of the contourf plot, and does not look very appealing. What I was trying to do is just draw the lines above my plot at the desired X coordinates from the original axis without having a new axis showing or extending the original

[Walter Roberson]

img = imread('cameraman.tif');

numrow = size(img,1);

marginy = numrow + double(max(img,[],1))/15;

ax = gca;
contourf(ax, img);
hold(ax, 'on');
plot(ax, marginy, 'r-');
hold(ax, 'off');
ylim(ax, [0 numrow]);
ax.Clipping = false;

[Anas Khan]

Thanks!