MATLAB GUI Zoom with multiple plots

Question

I have 2 plots in a MATLAB gui and i want to link them together so a zoom on one plot zooms the other.

Unlike similar questions i have seen on linking plots neither my x data or y data is shared by either graph, but it is related.

My data consists of the heights of land measured by a plane flying over them over a period of 5 seconds.

Plot 1 : The height of land

y: height = [10,9,4,6,3];
x: time = [1,2,3,4,5];

Plot 2 : land coordinates

y: latitude = [10,20,30,40,50];
x: longitude = [11,12,13,14,15];

If the user zooms in the x axis on Plot 1, for example showing the first 3 seconds of flight I want to zoom the x and y-axis of Plot 2 so only the first 3 longitude & latitude coordinates in the longitude & latitude arrays are shown.

Is this possible?

grantnz grantnz · Accepted Answer · 2013-09-30T05:24:13

You'll need a function that does the mapping of height & time to lat & longitude and then sets the limits based on the mapped values.

The following function does this job:

function syncLimits(masterAxes,slaveAxes)
% Sync a slave axes that is plot related data.
% Assumes each data point in slave corresponds with the data point in the
% master at the same index.

% Find limits of controlling plot
xRange = xlim(masterAxes);
% Get x data
x1Data = get(get(masterAxes,'children'),'XData');
% Find data indices corresponding to these limits
indices = x1Data >= xRange(1) & x1Data <= xRange(2);
if any(indices)
    % Set the limits on the slave plot to show the same data range (based
    % on the xData index)
    x2Data = get(get(slaveAxes,'children'),'XData');
    y2Data = get(get(slaveAxes,'children'),'YData');
    minX = min(x2Data(indices));
    maxX = max(x2Data(indices));
    minY = min(y2Data(indices));
    maxY = max(y2Data(indices));
    % Set limits +- eps() so that if a single point is selected
    % x/ylim min/max values aren't identical
    xlim(slaveAxes,[ minX - eps(minX) maxX + eps(maxX)  ]);
    ylim(slaveAxes,[ minY - eps(minY) maxY + eps(maxY)  ]);
end

end

You can then get the height v time plot to call this function whenever it is zoomed or panned.

height = [10,9,4,6,3];
time = [1,2,3,4,5];

latitude = [10,20,30,40,50];
longitude = [11,12,13,14,15];

% Plot Height v Time
h1 = figure;
a1 = gca;
plot(time,height);
title('Height v Time');


% Plot Lat v Long
figure;
a2 = gca;
plot(longitude, latitude);
title('Lat v Long')

% Set-up Callback to sync limits
zH = zoom(h1);
pH = pan(h1);
set(zH,'ActionPostCallback',@(figHandle,axesHandle) syncLimits(axesHandle.Axes,a2));
set(pH,'ActionPostCallback',@(figHandle,axesHandle) syncLimits(axesHandle.Axes,a2));

The code would be simpler if your plots are generated by a function as your could nest the syncLimits function and make use of the time, lat & long data directly. You could also pass this data into the syncLimits function which again would be a bit less code but you only have to write syncLimits once (and I've already done it!).

MATLAB GUI Zoom with multiple plots

2 Answers