MATLAB: How to identify which bar is clicked in a BAR plot

MATLAB

I want be able to click on a bar of the histogram and identify which bar was clicked.

Best Answer

The ability to do this in MATLAB is not available. However it is possible to write MATLAB code that allows expected behaviour.

The code uses the "ButtonDownFcn" to detect the mouse click. Once the mouse is clicked the function "mouse_fcn" is invoked. This function computes the bar which is selected based on the mouse position and returns a logical vektor that indicates which bar was selected.

h = bar(rand(1,5));
barclick(h)

You can use this to then execute your own custom function. Please note that the code will need modification in case if you have a bar groups.

function barclick(hbar)
xd = get(get(hbar,'children'),'XData');
yd = get(get(hbar,'children'),'YData');
set(gcf,'WindowButtonDownFcn',{@mouse_fcn,xd,yd});
function mouse_fcn(h,cnc,xd,yd)
cp = get(gca,'CurrentPoint');
id = and(~sign(sum(sign(cp(1)-xd(2:3,:)))),~sign(sum(sign(cp(3)-yd(1:2,:)))))

Related Solutions

MATLAB: How to get the point under mouse click on the plot or histogram

You can use the ButtonDownFcn function. Here's a demo you can run. It prints the selected bar index to the command window.

figure(); 
h = histogram(randn(10)); 
h.ButtonDownFcn = @clickHistFcn; 
function clickHistFcn(hObj,event)
% Get the bar edges and click coordinate

edges = hObj.BinEdges; 
click = event.IntersectionPoint; 
% Determine which bar was clicked

barIdx = find(click(1) >= edges, 1, 'last');
% Do whatever you want with that....
fprintf('bar %d selected.\n',barIdx)
end

Note, this code above does not ignore empty bar bins. For example, try it with these data.

h = histogram([rand(1,20),rand(1,20)+5],10)

If you'd like to ignore empty bars,

function clickHistFcn(hObj,event)
% Get the bar edges and click coordinate
edges = hObj.BinEdges; 
values = hObj.Values;
edges([false,values==0]) = [];  %remove edges that contain empty bars
click = event.IntersectionPoint; 
% Determine which bar was clicked
barIdx = find(click(1) >= edges, 1, 'last');
fprintf('bar %d selected.\n',barIdx)
end

MATLAB: Is the “ButtonDownFcn” callback for the axes not activated when I click on an object in the axes

An axes' "ButtonDownFcn" callback is only executed when you click on the axis itself, not the objects in the axis. The "ButtonDownFcn" callback for the child objects will be executed instead.

If you want the axes' "ButtonDownFcn" callback function to be executed regardless of where you click in the axes, try the following:

1. Set the "HitTest" property for the axis' child objects to 'off'. The "HitTest" property determines whether the object can become the current object when it is clicked on. If the "HitTest" property is set to 'off', then the object below it will become the current object, which could be another of the axes' child objects or the axes itself. If all of the axes' child objects have their "HitTest" property set to 'off', then the axes will become the current object and its "ButtonDownFcn" callback will be executed.

set(h,'HitTest','off')

2. Specify the desired callback function as the figure's "WindowButtonDownFcn" property. The "WindowButtonDownFcn" callback is executed whenever you click in the figure, and is executed before the "ButtonDownFcn" callback of any objects, including the figure itself.

set(gcf,'WindowButtonDownFcn','disp(''axis callback'')')

3. Define the "ButtonDownFcn" callbacks for the axes' child objects, so they have the same effect as calling the axes' "ButtonDownFcn" callback. This may include determining the object's Parent (the axes), and passing its handle as an input instead of the object's handle.

set(h,'ButtonDownFcn','disp(''axis callback'')')

Best Answer

Related Solutions

MATLAB: How to get the point under mouse click on the plot or histogram

MATLAB: Is the “ButtonDownFcn” callback for the axes not activated when I click on an object in the axes

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