# Legend for a graph displaying multiple runs

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Egle on 6 Apr 2017
Commented: Egle on 7 Apr 2017
Hello,
I have a working code for calculation of agch. I now want to see how different values of input Z affect the final results. I managed to plot runs with different Z values on one graph using hold on.
function [angle, alpha, al, agch, Al, Ag] = getanglech
[D, A, R] = geom();
[n, m] = setglblch();
X = setX();
[Xlm, aglm] = martineli();
for Z = 5:20
angle = arrayfun( @(X) fzero( @(angle) equationsch (angle, X, D, A, R, m, n, Z) , [1E-4, pi-1E-4]), X );
Ag = (R^2)*(pi-angle+0.5*sin(2*angle)) ;
Al = (R^2)*(angle-0.5*sin(2*angle)) ;
Slw = 2*R*angle ;
alpha = (4*Al)./(Slw*D) ;
al = Al/A ;
agch = Ag/A ;
p=loglog(Xlm, aglm, 'o', X, agch);
p(1).MarkerEdgeColor = [0 0 0 ];
xlabel('X')
ylabel('ag')
legend ('Martinelli', 'Chisholm')
legend('Location','best')
hold on
end
end
However, the legend is messy (picture attached). It should be clear in the plot which value of Z each line represents. Also, the Martinelli data should only have on entry in the legend and not every second. Can this be done? Any help appreciated. %

Joseph Cheng on 6 Apr 2017
you can look into specifying which points/lines are plotted in the legend() help documentation.
I made a quick example that you can see what is going on first of all then how to define which ones get into the legend
x =0:.1:10;
figure(1),clf
hold on
for ind = 1:10
p(ind,:) = loglog(ind,ind.^ind+ind,'o',x,x.^ind+ind);
p(ind,1).MarkerEdgeColor = [0 0 0 ];
xlabel('X')
ylabel('ag')
legend ('Martinelli', 'Chisholm')
legend('Location','best')
ltext(ind,:) = [{['point z=' num2str(ind)]},{['line z=' num2str(ind)]}]
end
title('all points were plotted')
pause(5)
legend off
legend([p(1,1); p(:,2)]',[ltext(1,1);ltext(:,2)]')
Egle on 7 Apr 2017
Hi Joseph this helped, thank you!