Add a colorbar for this quiver plot

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mohammad mortezaie
mohammad mortezaie 2025-1-17
评论： Voss 2025-1-17
Ran in:
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

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采纳的回答

Voss
Voss 2025-1-17
编辑：Voss 2025-1-17
Ran in:
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
  2 个评论
Voss
Voss 2025-1-17
You're welcome! Any questions, let me know. Otherwise, please "Accept" this answer. Thanks!

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更多回答（1 个）

Sandeep Mishra
Sandeep Mishra 2025-1-17
编辑：Sandeep Mishra 2025-1-17
Ran in:
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!
  2 个评论
mohammad mortezaie
mohammad mortezaie 2025-1-17
Thank you.
I want a plot without these filled circles. I need only color vectors.
Is there a code to solve this?
mohammad mortezaie
mohammad mortezaie 2025-1-17
Actually I need a quiver plot with colored vectors.

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