Add a colorbar for this quiver plot

I wrote a code to have a quiver plot as I attached here. I want to add a colorbar to this code as it shows the magnitude of the vectors. How can I do that?

nu1=3.87e5;
nu2=0.46e5;
v_m=2.84e5;
v_p=7.18e5;
% 
% nu1=8.4;
% nu2=1;
% v_m=1;
% v_p=2.5;

s=1;
s1=-1;
kesi=1;
kesi1=-1;

DeltaSO=41.9e-3;
alpha=1;
A=0.0;
hbar=1;
V=0;

iform=complex(0.0,1.0);

for i=1:25

    k_x=-0.3+2*(i-1)*0.3/25;

    for j=1:25
        k_y=-0.3+2*(j-1)*0.3/25;

        sigmax=[0 1; 1 0];
        sigmay=[0 -iform; iform 0];
        sigmaz=[1 0; 0 -1];
        sigma0=[1 0; 0 1];

        H1=hbar*k_x*nu1*sigmay-hbar*k_y*(s*nu2*sigmax+kesi*v_m*sigma0+kesi*v_p*sigmaz)+DeltaSO*(alpha-s*kesi)*sigmax+A*(s*sigmaz-kesi*sigmax)+V*sigma0;
        H2=hbar*k_x*nu1*sigmay-hbar*k_y*(s1*nu2*sigmax+kesi*v_m*sigma0+kesi*v_p*sigmaz)+DeltaSO*(alpha-s1*kesi)*sigmax+A*(s1*sigmaz-kesi*sigmax)+V*sigma0;
        H3=hbar*k_x*nu1*sigmay-hbar*k_y*(s*nu2*sigmax+kesi1*v_m*sigma0+kesi1*v_p*sigmaz)+DeltaSO*(alpha-s*kesi1)*sigmax+A*(s*sigmaz-kesi1*sigmax)+V*sigma0;
        H4=hbar*k_x*nu1*sigmay-hbar*k_y*(s1*nu2*sigmax+kesi1*v_m*sigma0+kesi1*v_p*sigmaz)+DeltaSO*(alpha-s1*kesi1)*sigmax+A*(s1*sigmaz-kesi1*sigmax)+V*sigma0;

        [v1,E1]=eig(H1);
        [v2,E2]=eig(H2);
        [v3,E3]=eig(H3);
        [v4,E4]=eig(H4);
        KX(i,j)=k_x;
        KY(i,j)=k_y;

        sx(i,j)=v4(:,2)'*sigmax*v4(:,2);
        sy(i,j)=v4(:,2)'*sigmay*v4(:,2);


    end                
end

quiver(KX,KY,sx,sy,1)

q.ShowArrowHead = 'off';
q.Marker = 'o';


Qu

Answer 1

[Voss]

figure
hold on
NColors = 10;
scale_factor = 0.02;
sr = sqrt(sx.^2+sy.^2);
[sr_min,sr_max] = bounds(sr,'all');
qidx = discretize(sr,linspace(sr_min,sr_max,NColors+1));
sx_tmp = sx.*scale_factor;
sy_tmp = sy.*scale_factor;
cmap = parula(NColors);
q = gobjects(1,NColors);
for ii = 1:NColors
    idx = qidx == ii;
    q(ii) = quiver(KX(idx),KY(idx),sx_tmp(idx),sy_tmp(idx),0,'Color',cmap(ii,:));
end
colormap(cmap)
colorbar

[mohammad mortezaie]

Thank you very much.

[Voss]

You're welcome! Any questions, let me know. Otherwise, please "Accept" this answer. Thanks!

Answer 2

[Sandeep Mishra]

Hi mohammad,

You can use the MATLAB ‘scatter’ function to add a colorbar to the quiver plot.

Refer to the following code snippet to implement the colorbar to a quiver plot:

% Calculating Magnitude
magnitude = sqrt(sx.^2 + sy.^2);

q = quiver(KX, KY, sx, sy, 1);
q.Marker = 'o';

% Adding Scatter to quiver plot
hold on
scatter(KX(:), KY(:), 20, magnitude(:), 'filled');  % '20' sets marker size

% Adding colorbar
colorbar; 

For more information, refer to the following MathWorks Documentation:

1. ‘scatter’ function: https://www.mathworks.com/help/releases/R2024b/matlab/ref/scatter.html
2. ‘colorbar’ function: https://www.mathworks.com/help/releases/R2024b/matlab/ref/colorbar.html

I hope this helps you!

[mohammad mortezaie]

Thank you.

I want a plot without these filled circles. I need only color vectors.

Is there a code to solve this?

[mohammad mortezaie]

Actually I need a quiver plot with colored vectors.