{"id":2645,"date":"2011-02-11T14:13:48","date_gmt":"2011-02-11T14:13:48","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/2011\/02\/11\/create-multi-column-plot-legends\/"},"modified":"2019-03-21T12:09:19","modified_gmt":"2019-03-21T16:09:19","slug":"create-multi-column-plot-legends","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2011\/02\/11\/create-multi-column-plot-legends\/","title":{"rendered":"Create Multi-Column Plot Legends"},"content":{"rendered":"
\r\n <\/introduction>\r\n

Brett<\/a>'s Pick this week is \"columnlegend,\"<\/a> by Simon Henin<\/a>.\r\n <\/p>\r\n

\r\nNOTE<\/strong>: Functionality similar to this File Exchange entry was added to MATLAB in R2018a. See the NumColumns Property<\/a> to legend.\r\n<\/p>\r\n\r\n

Today's Pick is another that is an author's first submission to the File Exchange. Simon shared a nice, easy-to-use function\r\n to create multi-column figure labels.\r\n <\/p>\r\n

MATLAB's built-in legend<\/tt><\/a> command suffices for most cases when there are few objects to differentiate. However, when the number of lines plotted, for\r\n instance, gets large, columnlegend<\/tt> shines. It enables one essentially to reshape the default n-by-one legend into a p-by-q one.\r\n <\/p>\r\n

Consider:<\/p>

nLines = 18;\r\nlegend_str = cell(nLines,1);\r\n\r\nmyColors = distinguishable_colors(nLines);<\/pre>
(See my previous post about distinguishable_colors<\/a>, or comment out the above line, and uncomment the following one.)\r\n   <\/p>
%myColors = jet(nLines);<\/span>\r\nt = 0:pi\/64:3*pi;\r\ndPhi = pi\/16;\r\nlineStyles = {'-'<\/span>, '--'<\/span>, ':'<\/span>, '-.'<\/span>};\r\nfor<\/span> ii=1:nLines,\r\n    plot(t,sin(t+dPhi*ii),...<\/span>\r\n        'linestyle'<\/span>, lineStyles{rem(ii-1,numel(lineStyles))+1},...<\/span>\r\n        'color'<\/span>, myColors(ii,:),...<\/span>\r\n        'linewidth'<\/span>,3);\r\n    hold on<\/span>;\r\n    legend_str{ii} = num2str(ii);\r\nend<\/span>\r\naxis([0 3*pi -1.15 1.6])\r\nlegend(legend_str,'location'<\/span>,'NorthWest'<\/span>)<\/pre>
 <\/p>\r\n   
Now consider how columnlegend<\/tt> improves the situation:\r\n   <\/p>
for<\/span> ii=1:nLines,\r\n    plot(t,sin(t+dPhi*ii),...<\/span>\r\n        'linestyle'<\/span>, lineStyles{rem(ii-1,numel(lineStyles))+1},...<\/span>\r\n        'color'<\/span>, myColors(ii,:),...<\/span>\r\n        'linewidth'<\/span>,3);\r\n    hold on<\/span>;\r\n    legend_str{ii} = num2str(ii);\r\nend<\/span>\r\naxis([0 3*pi -1.15 1.6])\r\ncolumnlegend(6,legend_str,'NorthWest'<\/span>);<\/pre>
 <\/p>\r\n   
That's better! columnlegend<\/tt> also conveniently provides a handle to the legend-containing axes, allowing you to tweak parameters (like position). Very\r\n      nice first effort, Simon!\r\n   <\/p>\r\n   
Let us know what you think<\/a>, or leave a comment for Simon here<\/a>.\r\n   <\/p>
One further note: in a comment<\/a> on his submission page, Simon mentioned that he had fixed an issue with plot markers. As of this writing, that modification\r\n      is still pending; it should be available shortly.\r\n   <\/p>\r\n