{"id":5452,"date":"2014-07-25T09:00:56","date_gmt":"2014-07-25T13:00:56","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=5452"},"modified":"2014-07-24T01:36:38","modified_gmt":"2014-07-24T05:36:38","slug":"append-entries-to-a-legend","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2014\/07\/25\/append-entries-to-a-legend\/","title":{"rendered":"Append entries to a legend"},"content":{"rendered":"
\r\n

Jiro<\/a>'s pick this week is legappend<\/tt><\/a> by Chad Greene<\/a>.\r\n <\/p>\r\n

Chad is no stranger to MATLAB Central. He has over 50 File Exchange entries<\/a>, and two of his entries have been highlighted (unit converters<\/a> and ccc<\/a>) in Pick of the Week. His entries are well-written, and like this one, many of his entries have published example files<\/a>.\r\n <\/p>\r\n

Many of you may know that the command legend<\/tt><\/a> creates one legend per axes.\r\n <\/p>

t = 0:.1:10;\r\nx1 = sin(t);\r\nx2 = cos(t);\r\nplot(t,x1,t,x2)\r\nlegend('Sine'<\/span>,'Cosine'<\/span>)<\/pre> 
Let's say that you wanted to add another line to this plot.<\/p>
x3 = sin(t).*cos(t);\r\nhold on<\/span>\r\nplot(t,x3,'--r'<\/span>)<\/pre> 
To add this entry to the legend, you would re-run the legend<\/tt> command with the three entries.\r\n   <\/p>
legend('Sine'<\/span>,'Cosine'<\/span>,'Sine*Cosine'<\/span>)<\/pre> 
Chad's legappend<\/tt> allows you to append new entries to an existing legend. This means that you can simply call it along with the new lines you\r\n      create.\r\n   <\/p>
% New figure<\/span>\r\nfigure;\r\nplot(t,x1,t,x2)\r\nlegend('Sine'<\/span>,'Cosine'<\/span>)\r\n\r\n% Add another line<\/span>\r\nhold on<\/span>\r\nplot(t,x3,'--r'<\/span>)\r\n\r\n% Append a new legend item<\/span>\r\nlegappend('Sine*Cosine'<\/span>)<\/pre> 
Great! You can also delete the last legend entry with the following command.<\/p>
legappend(''<\/span>)<\/pre>
If you want to see more examples, check out his published example<\/a>.\r\n   <\/p>\r\n   
Chad explains that legappend<\/tt> simply deletes the current legend and recreates the updated legend. This is a good example of how you can take a normal mode\r\n      of operation and tweak it in order to adapt it to your needs.\r\n   <\/p>\r\n   
Give it a try and let us know what you think here<\/a> or leave a comment<\/a> for Chad.\r\n   <\/p>