legend inside a For loop

Hello All,

I am trying to have a plot legend update after each iteration but I am having a hard time coming up with a solution. I have tried different techniques but nothing has worked so far.

Basically, I would like to have the legend print all values of "n". For example, Fin = n1, Fin=n2, etc. Using the provided code, I only get the legend for the last value of "n". Any suggestions would be greatly appreciated.

for n = 0:n_fins_inter:n_fins;
    plot(array.Velocity_Plot(array.Nf_Plot==n),array.Pres_Drop_Plot((array.Nf_Plot==n)))
    legend({sprintf('fin =%f\n',n)},'Location','southeast')
    hold on
end

Thank you.

Answer 1

[Walter Roberson]

for n = 0:n_fins_inter:n_fins;
    dn = sprintf('fin =%f', n);
    plot(array.Velocity_Plot(array.Nf_Plot==n),array.Pres_Drop_Plot((array.Nf_Plot==n)), 'DisplayName', dn);
    hold on
end
legend('show', 'Location', 'southwest')

Answer 2

[John Doe]

Hello,

Not quite sure what your end goal is here, multiple figures with different legends or 1 figure with many legends.

To make multiple figures each with a different legend you can use a for loop like this.

% Multiple plots using for loop 
ledgName = {'n1';'n2';'n3';'n4';'n5'}
 for k = 1:1:5
    figure(k)       
        plot(someData(:,k));
            legend(sprintf('%s', ledgName{k}),'Location','southeast'))
 end

To plot all of the data on the same figure you don't have to use a for loop. I have offered to options one with and without a for loop.

Tip: The legend should be outside of the for loop.

 % Without a for loop 
ledgName = {'n1';'n2';'n3'}
figure(1)
plot(xdata(:,1),ydata(:,1),xdata(:,2),ydata(:,2),xdata(:,3),ydata(:,3)) % and so on
legend(ledgName) 
title('A Title')
xlabel('X Axis')
ylabel('Y Axis')

%With a for loop 
figure(1)
hold on
ledgName = {'n1';'n2';'n3';'n4';'n5'}
for k = 1:5 
    plot(x,someData(:,k))
end
legend(ledgName)

% If you don't want to use a cell array for legend names then use this. But this is pointless
legend('N1','N2','N3')

To create a cell array for your legend using a for loop per your comment below:

for k = 1:8
    names{k} =  sprintf('N%d',k)
end

[Fabiano Da Mota]

Hello John,

Thank you for answering. I would like to have one figure with many legends. For example, one figure with 4 curves and 4 legends - 1 legend for each curve. I would like each legend to display the value of "n". Please let me know if that makes more sense.

Thank you once again.

[Fabiano Da Mota]

Hello again John,

Correct, I don't need a loop to do the legend. I am trying to automate the process; If I change the number of "n" than I have to physically update the legend. That is one of the reasons that I tried;

legend({sprintf('fin =%f\n',n)},'Location','southeast')

However, with this approach, I am only able to get the legend for the last value of "n".

Thank you once again.

[John Doe]

Store your legends in a cell array and use a for loop to update the cell array if necessary.

Please accept the answer once you're happy. :)