What should I do to not show the legend for all the plots?

问题

Here is my code:

N=100;
n=50;
tau=0.001;
h=0.01;
lambda=tau/h;
mu=lambda/2;
u=zeros(N,n);
u1=zeros(N,n);
u2=zeros(N,n);
phi=zeros(n,1);
for i=1:n
    for j=1:N
        u(j,i)=cos(2*pi*i*(j-1)*h);
        u1(j,i)=cos(2*pi*i*((j-1)*h-tau));
    end

    for j=2:N
        u2(j,i)=u(j,i)-lambda*(u(j,i)-u(j-1,i));
    end
u2(1)=0;
phi(i,1)=2*pi*i/N;    
end
uf=zeros(n,1);
uf1=zeros(n,1);
uf2=zeros(n,1);

for i=1:n
   for j=1:N
       uf(i,1)=uf(i,1)+(u(j,i)*exp(-1i*(j-1)*phi(i,1)))/100;
       uf1(i,1)=uf1(i,1)+u1(j,i)*exp(-1i*j*phi(i,1))/100;
       uf2(i,1)=uf2(i,1)+(u2(j,i)*exp(-1i*(j-1)*phi(i,1)))/100;
   end
end
final=zeros(n,1);
for i=1:n
    final(i,1)=-(h/(1i*tau))*(log(uf2(i)/uf(i)));
end


figure;
hold on 
z=1:1:n;
b = real(final(z,1));
%plot(phi(z,1),b,'o');
c = imag(final(z,1));
%plot(phi(z,1),c,'-');
%plot(phi(z,1),0,'-');
plot(phi(z,1),b,'ro',phi(z,1),c,'ko',phi(z,1),0,'k-');
legend('Real','Imaginary');
legend ('Location','NorthWest');
xlabel('Reduced Wavenumber')
ylabel('Modified Wavenumber')

I am plotting a line at y=0 for reference. I do not want them in legend. But I am getting this figure:

How do I resolve this?

回答1:

Instead of plotting everything with one plot-command, do it like this:

plot(phi(z,1),b,'ro'); hold on
plot(phi(z,1),c,'ro'); hold on
plot(phi(z,1),0,'k-'); hold off

legend('Real','Imaginary','Location','NorthWest');
xlabel('Reduced Wavenumber')
ylabel('Modified Wavenumber')

You shouldn't have problems then.

The actual reason is, that the legend is called differently in this case. The more elegant solution offers the answer of Magla.

回答2:

Legends in matlab should be called like this

plot(phi(z,1),b,'ro',phi(z,1),c,'ko',phi(z,1),0,'k-');
legend( {'Real','Imaginary'} , 'Location', 'NorthWest');

where legend labels are stored in a cell array of strings {...}. Location is a parameter to be placed either with the legend call (like in the above code) or outside the function by using the set function

h = legend({'Real','Imaginary'});
set(h, 'Location','NorthWest');

This gives

来源：https://stackoverflow.com/questions/18895523/what-should-i-do-to-not-show-the-legend-for-all-the-plots

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matlab

plot

matlab-figure