{"id":6691,"date":"2016-03-25T09:00:55","date_gmt":"2016-03-25T13:00:55","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=6691"},"modified":"2016-03-25T08:39:21","modified_gmt":"2016-03-25T12:39:21","slug":"interactive-legend-in-r2016a","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2016\/03\/25\/interactive-legend-in-r2016a\/","title":{"rendered":"Interactive Legend in R2016a"},"content":{"rendered":"\n

Jiro<\/a>'s pick this week is a feature that allows you to create interactive legends using callbacks<\/a>.<\/p>

This week, I'd like to highlight one of the new R2016a features<\/a> that just came out a couple of weeks ago. There are so many exciting features<\/a>, and the one I'll be talking about today is related to a Pick<\/a> from a while ago on clickableLegend<\/tt><\/a> by one of our ex-MathWorkers, Ameya<\/a>. Ameya's entry allowed you to create an interactive legend for turning on and off particular lines.<\/p>

With R2016a, you can specify custom actions that get executed when one clicks on a legend item. Let's try with the following data set.<\/p>

x = linspace(0,10);\ny1 = sin(x);\ny2 = cos(x);\ny3 = sin(x) + cos(x);\ny4 = sin(x) .* cos(x);\nplot(x,y1,x,y2,x,y3,x,y4)\n<\/pre>
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Toggle Visibility<\/b><\/p>
To use this new feature, you first create a function that defines the specific action you want to perform. For example, the following function toggles the visibility of the line.<\/p>
function<\/span> action1(src,event)\n% This callback toggles the visibility of the line<\/span>\n\nif<\/span> strcmp(event.Peer.Visible,'on'<\/span>)   % If current line is visible<\/span>\n    event.Peer.Visible = 'off'<\/span>;      %   Set the visibility to 'off'<\/span>\nelse<\/span>                                 % Else<\/span>\n    event.Peer.Visible = 'on'<\/span>;       %   Set the visibility to 'on'<\/span>\nend<\/span>\n<\/pre>
Then, you assign the function to the ItemHitFcn<\/tt> property of the legend<\/tt><\/a> object.<\/p>
hLeg = legend('Line 1'<\/span>,'Line 2'<\/span>,'Line 3'<\/span>,'Line 4'<\/span>);\nhLeg.ItemHitFcn = @action1;\n<\/pre>
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Blinking Line<\/b><\/p>
Here is a different function that blinks the line that is clicked.<\/p>
function<\/span> action2(src,event)\n% This callback causes the line to \"blink\"<\/span>\n\nfor<\/span> id = 1:3                        % Repeat 3 times<\/span>\n    event.Peer.LineWidth = 3;       % Set line width to 3<\/span>\n    pause(0.2)                      % Pause 0.2 seconds<\/span>\n    event.Peer.LineWidth = 0.5;     % Set line width to 0.5<\/span>\n    pause(0.2)                      % Pause 0.2 seconds<\/span>\nend<\/span>\n<\/pre>
hLeg.ItemHitFcn = @action2;\n<\/pre>
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Displaying Line Elsewhere<\/b><\/p>
Here is another function that displays the line on a different set of axes.<\/p>
function<\/span> action3(src,event,hAx)\n% This callback displays the selected line on a different set of axes<\/span>\n\nx = event.Peer.XData;                   % Get X data of interest<\/span>\ny = event.Peer.YData;                   % Get Y data of interest<\/span>\nplot(hAx,x,y,'Color'<\/span>,event.Peer.Color)  % Plot data with the same color<\/span>\ntitle(hAx,event.Peer.DisplayName)       % Set the title to the line name<\/span>\n<\/pre>
subplot(2,1,1)\nplot(x,y1,x,y2,x,y3,x,y4)\nhLeg = legend('Line 1'<\/span>,'Line 2'<\/span>,'Line 3'<\/span>,'Line 4'<\/span>);\nhAx = subplot(2,1,2);\nhLeg.ItemHitFcn = @(src,event) action3(src,event,hAx);\n<\/pre>
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Comments<\/b><\/p>
Let us know what you think here<\/a>.<\/p>
Refer to the ItemHitFcn<\/tt><\/a> property for the explanation of the event<\/tt> data structure.<\/p>