How can I use legend for plotting dynamically sized matrix?

I'm trying to plot a matrix that's returned from a function. The size of the matrix is 3xN, N is accepted with input. This is what I'm trying to get to work:

for i = 1:length(T(1,:))
    plot(T(:,i));
    legend([ num2str(i-1) '. Generation']);
end

but the legend is assigned only to the plot of the first column of the matrix for i's max value. Is it possible to get it to work properly?

Answer 1

[Adam Danz]

Your loop is continuously overwriting the legend and only including the most recently plotted line. You actually don't need a loop at all.

T = randi(10,3,5);  % fake data
plot(T)
legendStr = compose('%d Generation',(1:size(T,2))-1);
legend(legendStr)

If, for whatever reason, you prefer to produce the plot within a loop, here is the correct way to do that.

T = randi(10,3,5);   % fake data
axes()
hold on
for i = 1:size(T,2)
    plot(T(:,i),'DisplayName', sprintf('%d Generation',i-1)); 
end
legend() % no need for inputs since we used DisplayName

[Emin Yilmaz]

Thank you, first one worked very well. I thought I somehow could do it in a loop.

[Adam Danz]

You could do it in a loop as my 2nd example shows but it's best to use the non-loop method. So, good choice! For plot(T), if T is a matrix, a line will be created for each column in T.

[Robin Amar]

Hello Adam,

As I had similar requirement, therefore, I tried your option 1 with my code.

But, I cannot see multiple entries in the Legend display.

My Code:

phi = linspace(-4*pi, 4*pi, 30);
legendStr = compose('Angle: %s', int2str(phi));
legend(legendStr);

The output is as seen below (only one entry for all the traces):

Actually, I expected the output to be something like (independent entry for every trace):

Any Suggestions...??

[Adam Danz]

I only see one line in your plot so there's only going to be one legend entry per line.