Plotting 2 streamlines on the same plot

Hi everyone.

I need to plot 2 different streamlines on the same plot. I was able to do it, but I can't insert a propper legend. My plot code is:

figure
a=streamline(XYe);
hold on
area(circ(1,:),circ(2,:),'FaceColor',Col,'EdgeColor',Col)
hold off
xlabel('x/a [adim.]','FontSize',25)
ylabel('y/a [adim.]','FontSize',25)

set(a,'Color','k')
legend('Stokes','Euler')

But the legend doesn't show the color of the lines correctly (both lines on the legend are blue, the default color of the streamline, and 'Euler' doesn't appear black on the legend, but it does appear black on the plot).

I know the use of set and the figures is not appropiate, and I know this is just a detail, but that's my problem, I want to understand figures, and "set". It would be very helpful if you could help me plot this, and also help me understand the mechanism of figures.

Thanks in advance.

José

Answer 1

[Ojas]

Hi,

I'm not sure if you could solve your problem, but I discovered the method to solve the problem. You insert "" as many times as the lines are which you do not want in the legend, and then add your actual name in the legend. Attaching the code for the same below. Here, I have the length of the streamlines as 9, hence I inserted my true label once, and then used "" 8 times. Hope this helps.

[startX,startY] = meshgrid(xbins(1:9), zbins(1));

figure(4);

axis equal

lineobj = streamline(X, Z, abs(u'), abs(v'), startX, startY);

for i=1:9

lineobj(i).LineWidth = 2;

end

hold on

A = scatter(x, z, 3, "red", "filled", "o", "MarkerEdgeColor","flat", "MarkerFaceColor","auto" );

hold off

xlabel("X")

ylabel("Z")

title("Streamlines plot")

legend("Force streamlines", "", "", "", "", "", "", "", "", "Particles")

legend('show')

Answer 2

[darova]

Use handlers properly

clc,clear

[x,y,z] = peaks(5);
h1 = plot(y,z,'r');
hold on
h2 = plot(y,0.9*z,'b');
hold off
legend('red','blue')
%legend([h1(1) h2(1)],'red','blue')

[José Irusta Solera]

The problem is that I can't choose the color in the function streamline, because apparently it doesn't work as the plot function. If I do this:

streamline(XY,'r')

Where XY is the result of the "stream2" function. With this, the program throws an error at the "streamline" function.

[darova]

Try this way:

h = streamline(x,y,u,v,startx,starty);
set(h,'color','r')

[José Irusta Solera]

That works on changing the color of the lines on the plot, but the problem is the legend. If I do that, and don't do anything on the legend, then the legend doesn't appear. If I use:

legend('show')

Then the legend shows "Stokes" (or "Euler") lots of times, according to the number of lines there are. I just need it to appear once, like in the image I presented. That's what I can't do.

Thank you.