How to plot a trajectory with varying colour?

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Maheedhar Korimi
Maheedhar Korimi 2023-2-23
评论： Voss 2023-2-24
I'm trying to plot the trajectory which also shows error characteristics visually.
Inputs: East(m), North(m), error(m)
error = sqrt((East_radar - North_GPS)^2 + (East_GPS - North_GPS)^2)
At present, I'm able to plot trajectory, with the marker indices representing the points where the error is high. I have implemented the code as seen below.
To make this visualization better, how can I represent the trajectory with varying colour representing error value? as shown below.
So, higherror represents Red and low error represents Green? Your assistance would relly help me.Thanks!
If my query is unclear, please revert.
figure()
plot(Radar_East, Radar_North,'LineStyle','-')
xlabel('East (m)')
ylabel('North (m)')
title('GPS EN plot')
hold on
plot(Radar_East(outliers),Radar_North(outliers),'o','MarkerSize',8);
legend('RADAR Trajectory','Outliers > 99 percentile')
hold off

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采纳的回答

Voss
Voss 2023-2-23
Ran in:
"I'm trying to assign an independent variable to a data point in 2D through colour."
You can choose any colour(s) you like.
Examples:
x = linspace(0,2*pi);
y = sin(x);
subplot(3,2,1)
c = x;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = x')
subplot(3,2,2)
c = y;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = y')
subplot(3,2,3)
c = cos(x);
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = cos(x)')
subplot(3,2,4)
c = y.^2;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = y^2')
subplot(3,2,5)
c = x.^2-4*pi^2*y.^2;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = x^2-4*pi^2*y^2')
subplot(3,2,6)
c = rand(size(x));
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = random')
figure
colormap(copper())
subplot(3,2,1)
c = x;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = x')
subplot(3,2,2)
c = y;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = y')
subplot(3,2,3)
c = cos(x);
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = cos(x)')
subplot(3,2,4)
c = y.^2;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = y^2')
subplot(3,2,5)
c = x.^2-4*pi^2*y.^2;
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = x^2-4*pi^2*y^2')
subplot(3,2,6)
c = rand(size(x));
surface([x;x],[y;y],[c;c],'FaceColor','none','EdgeColor','interp','LineWidth',2);
title('color = random')
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Maheedhar Korimi
Maheedhar Korimi 2023-2-24
That's what I'm looking for, thank you for the help, that was a silly mistake on my part.
Cheers!!
Thank you @Voss

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更多回答（2 个）

Cameron
Cameron 2023-2-23
编辑：Cameron 2023-2-23
I don't think there is a way to do this using just one plot. My quick solution would be to do something like this
x = 0:0.05:2*pi; %sample x data
y = sin(x); %sample y data
c = hsv(length(x)); %hsv values over the length of x
hold on %hold the graph
for ii = 1:length(x)-1
plot(x(ii:ii+1),y(ii:ii+1),'-','Color',c(ii,:)) %plot
end
hold off
Not the most elegant solution, but if really want to do it, this is a way. One problem with this approach would be if you have few data points. You could spline or smooth your data though.
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Maheedhar Korimi
Maheedhar Korimi 2023-2-23
@Cameron Thanks for the quick response. Due to confidentiality, I couldn't share the actual trajectory (which covers an area of 9 square Kilometer). So the plot is huge and contains many data points.
In your solution, I cannot assign colour to the error value, so I cannot visualize the error properly, so I don't think this is the right solution.
Appreciate your effort, Thanks
Maheedhar Korimi
Maheedhar Korimi 2023-2-23
@John D'Errico Thanks for understanding my question i.e., using colors to represent underlying data is what I'm looking for.
Cheers for the comment.

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Les Beckham
Les Beckham 2023-2-23
Take a look at this Answer which shows a trick for doing this using surface.
https://www.mathworks.com/matlabcentral/answers/5042-how-do-i-vary-color-along-a-2d-line#answer_7057
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Les Beckham
Les Beckham 2023-2-24
"provide more details (your data and the code you are using to plot it".
Are we supposed to guess what you are trying to plot (and how)?
Maheedhar Korimi
Maheedhar Korimi 2023-2-24
I have attached the code and data in my previous comment, please run it, you'll see a trajectory(radar) with errors (> 99 percentile) in comparision with GPS data, represented as marker indices.
So, instead of representing the errors as marker indices, I would like to show the errors in the form of colour (maybe of colourmap: jet), where blue represents low error and red represents high error in the data.
If you have any further questions, please feel free to ask.
My apologies if I haven't communicated properly.

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