Adding a legend manually for a plot generated by a loop

2 次查看（过去 30 天）
Osh
Osh 2016-1-26
评论： Osh 2016-1-26
Hi,
I am generating a plot in Matlab one point at a time depending on how a condition is satisfied within a loop:
for i=1:size(Ind,1)
if(Ind(i)==1)
c='ro';
elseif(Ind(i)==2)
c='bo';
elseif(Ind(i)==3)
c='go';
end
plot(i,Y(i),c) %plotting some other value with the color chosen.
hold on
end
How do I add a legend entry to this? I want to associate the index position(1,2 and 3) to red,blue and green in the legend.
Thanks!

请先登录，再回答此问题。

采纳的回答

jgg
jgg 2016-1-26
编辑：jgg 2016-1-26
I think the issue is that you don't want to generate the plot like that; it's slow and makes it hard to label. Check out this solution instead:
Y = 10*rand(100,1); %your data
Ind = rand(100,1) > 0.5;
Ind = Ind + (rand(100,1) > 0.75);
Ind = Ind + 1; %an index corresponding to the group/colour of Y
Vals = [1:100]'; %the X-axis, or location of Y
plot(Vals(Ind == 1),Y(Ind ==1), 'ro', Vals(Ind == 2), ...
Y(Ind == 2), 'bo', Vals(Ind == 3), Y(Ind == 3), 'go')
legend('Red Data', 'Blue Data', 'Green Data')
This is much more efficient and you don't have to loop over all your points.
So, in your example, you would just go:
i = [1:size(Ind,1)];
plot(i(Ind == 1),Y(Ind ==1), 'ro', i(Ind == 2), ...
Y(Ind == 2), 'bo', i(Ind == 3), Y(Ind == 3), 'go')
legend('Red Data', 'Blue Data', 'Green Data')

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Legend 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by