Legend and Colors for Iteration function

Good Day;

I need the steps that I can add Legend to my iteration function, where there are four curves, therefore, for each curve there must have specific color and legend that point to it.

Many Thanks

Answer 1

[Adam Danz]

Use the displayname property to assign the legend string and use the "color" property to set the line color.

% Define colors 
n = 12; 
colors = jet(n); 

% Plot within loop
hold on % Important!
for i = 1:n
    plot(1:5, rand(1,5), '-', 'Color', colors(i,:),...
        'DisplayName', sprintf('Line #%d',i));
end
legend()

[A.J.M]

Dear Mr.Adam Danz ;

the result as shown in the figure, and my code as shown below, where is my mistake please.

n = 4; 
colors = jet(n); 
hold on
figure(1)
for i=1:length(Rytov_var)
    for j=1:length(Hp)
    plot(Z, PDF_Hp, '-', 'Color', colors(i,:),...
        'DisplayName', sprintf('Line #%d',i)); 
    end
end
 grid on
legend('σ^2_I=0.1','σ^2_I=0.2','σ^2_I=0.5','σ^2_I=0.8')

[Adam Danz]

1. Use numel() instead of length().
2. See the 4 "% <------changed" comments
3. Am I correct that the i-loop controls the color and the j-loop controls the legend string? Where are those values (=0.1, =0.2, etc) coming from? If those are variable values, use those variable to assign the numbers rather than hard-coding them. There's no sense in using DisplayName and defining the legend strings in legend().

n = numel(Rytov_var); % <------changed
colors = jet(n); 
hold on
figure(1)
for i=1:n % <------changed
    for j=1:numel(Hp) % <------changed
    plot(Z, PDF_Hp, '-', 'Color', colors(i,:),...
        'DisplayName', sprintf('σ^2_I=%.1f',i));  % ?????????
    end
end
 grid on
legend()% <------changed

[A.J.M]

Mr. Adam Danz;

Where are those values (=0.1, =0.2, etc) coming from? Yes these value are varibles,and it belong to Rytov_var varible. I assigned it but the same result.

[Adam Danz]

Ok, then

 plot(Z, PDF_Hp, '-', 'Color', colors(i,:),...
        'DisplayName', sprintf('σ^2_I=%.1f',Rytov_var(i))); 
    %                                       ^^^^^^^^^^^^

but that will result in duplicate colors and legend strings. Since I don't know what the two loops are supposed to do, I cannot suggest an alternative. Perhaps the 1st loop controls the legend string and the 2nd loop controls the color? If so,

n = numel(Hp); 
colors = jet(n); 
hold on
figure(1)
for i=1:numel(Rytov_var)
    for j=1:n
        plot(Z, PDF_Hp, '-', 'Color', colors(j,:),...
            'DisplayName', sprintf('σ^2_I=%.1f',Rytov_var(i))); 
    end
end
grid on
legend()

[A.J.M]

Mr. Adam Danz;

I'm sorry if I disturb you. The result as shown in the figure. Below is the original function that I want to plot it. The plot between PDF_Hp and the distance Z. I appreciate your efforts.

Z=100:250:5000;          %Distance Between The Transmitter and Reciever in m
Rytov_var=[0.1,0.2,0.5,0.8];
for i=1:length(Rytov_var)
    for j=1:length(Hp)
        A1(i,j)=1./(Hp(j).*sqrt(2*pi*Rytov_var(i)));
        A2(i,j)=((log(Hp(j))+0.5.*Rytov_var(i)).^2)./2.*Rytov_var(i);
        PDF_Hp(i,j)=A1(i,j).*exp(-(A2 (i,j)));
    end
end

[Adam Danz]

Take a few moments to understand what your loops are doing. I don't know what they are supposed to do and I can't run the code since there are missing variable values (e.g. Hp).

If you understand how my solution assigns color and assigns the legend string, I think you'll figure out what needs changed in your code. But since I don't understand what the loops are for and how color is supposed to be assigned and how the legend string is supposed to be assigned, I can't propose a solution.

[A.J.M]

Thanks a lot Mr. Adam Danz.

[Adam Danz]

No problem, I'd be glad to help further if needed.

[A.J.M]

That's very kind of you Mr. Adam Danz.

Accept my respect

[A.J.M]

Good day Mr. Adam Danz;

This is my code, I plotted without loop, the new problem is the legend colors don't match the curves.

Z=100:250:5000;                                          %Distance Between The Transmitter and Reciever in m
pointing_Err_angle=1*10^-5;                        %Pointing Error Angle in mrad        
lambda=1550e-9;                                          %Wavelength in nm
wo=5*10^-2;                                                  %Beam Waist  at Z=0 in m
 Cn=sqrt(5e-15);                                          %Refractive Index Structure Parameter
% --------------------Calculation Section------------------------------
k=2*pi/lambda;                                                              %The number of optical wave
po=(0.55*(Cn)^2*k^2*Z).^(-3/5);                                    %The Coherence Length
E=(1+2*wo^2./po.^2);
wz=wo*(1+E.*((lambda.*Z)./(pi*wo^2)).^2).^(1/2);           %The Beam Waist 
r=Z*(pointing_Err_angle);                                                %The Radial Displacement B
%----------------------------------------Calculate Hp-------------------
v=(sqrt(pi)*a)./(sqrt(2)*wz);
a0=(erf(v)).^2;                       %Maximal Fraction of Collected Power at r=0
Wzeq=sqrt(wz.^2*((sqrt(pi).*erf(v))/(2*v.*exp(-v.^2))));    
Hp=a0.*exp((-2*r.^2)./((Wzeq).^2));                       
%--------------------------Intensity Distribution---------------
Rytov_var=[0.1,0.2,0.5,0.8];            %Log irradiance variance (Roytov variance)
for i=1:length(Rytov_var)
    for j=1:5:length(Hp)
A1(i,j)=1./(Hp(j).*sqrt(2*pi*Rytov_var(i)));
A2(i,j)=((log(Hp(j))+0.5.*Rytov_var(i)).^2)./2.*Rytov_var(i).^2;
PDF_Hp(i,j)=A1(i,j).*exp(-(A2(i,j)));
    end
end
%--------------------------Plot Section---------------------------------
z=1250:1250:5000;               %Distance for Plot Purpose
figure(1)
semilogy(z,PDF_Hp,'LineWidth',4);
xlabel('The Distance Z')
ylabel('The Probability Density Function ')
title('The PDF of Hp Vs The Distance')
legend('σ^2_I=0.1','σ^2_I=0.2','σ^2_I=0.5','σ^2_I=0.8')
grid on
figure(2)
semilogy(Rytov_var,PDF_Hp,'LineWidth',3);
xlabel('Roytov variance')
ylabel('The Probability Density Function ')
title('The PDF of Hp Vs Rytove Variance')
legend('σ^2_I=0.1','σ^2_I=0.2','σ^2_I=0.5','σ^2_I=0.8')
grid on

[Adam Danz]

I cannot run the full code because "a" is not defined.

v=(sqrt(pi)*a)./(sqrt(2)*wz);

Error:
Unrecognized function or variable 'a'.

[A.J.M]

Sorry for this mistake;

a=0.5e-2;

[Adam Danz]

I see the problem. Look at the values you're plotting.

semilogy(z,PDF_Hp,'LineWidth',4);

PDF_Hp =
  Columns 1 through 12
       59.204            0            0            0            0       74.572            0            0            0            0       130.59            0
       33.684            0            0            0            0       41.243            0            0            0            0        66.92            0
       5.2821            0            0            0            0       5.3479            0            0            0            0       5.1881            0
      0.42448            0            0            0            0      0.30818            0            0            0            0      0.12088            0
  Columns 13 through 16
            0            0            0       242.89
            0            0            0       112.93
            0            0            0       4.5326
            0            0            0     0.032869

A line is created for each column so your plot actually has 16 lines, not 4.

The reason they don't appear is because in a log plot, 0 is not defined. However, those line objects are still produced - they are just not shown. As evidence of that, check out the 16 object handles.

h = semilogy(z,PDF_Hp,'LineWidth',4)
%     h = 
%       16×1 Line array:
%     
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line
%       Line

The reason the "wrong" colors are defined is because you're only asking for the first 4 objects to appear in the legend. But objects 2-3-4 are all non-visible lines.

legend('σ^2_I=0.1','σ^2_I=0.2','σ^2_I=0.5','σ^2_I=0.8')

Solution

Get rid of the columns with 0s in PDF_Hp

[A.J.M]

Thanks a lot, Mr. Adam Danz, the problem was solved. I appreciate your hard efforts

Accept my respect.