Legend command does not distinguish the colours specified in the plot command

Here is my code. The signals are send from the Simulink to the workspace and the save format is ' Structure with time' . The code does displays the plot but in the legend first three Machines are shown with same red colour and the fourth machine i.e. Machine 19 is depicted by blue colour. Can anyone help me correct this?

figure

plot(Vpu_15.time, Vpu_15.signals.values,'r')
hold on
plot(Vpu_16.time, Vpu_16.signals.values,'b')
hold on
plot(Vpu_17.time, Vpu_17.signals.values,'g')
hold on
plot(Vpu_19.time, Vpu_19.signals.values,'k')
hold off

xlabel('Time (s)')
ylabel('Voltage (pu)')
title('Machine Voltages')
legend('Machine 15', 'Machine 16', 'Machine 17', 'Machine 19')
legend('TextColor', 'black')

[the cyclist]

Can you upload the data we need to recreate your plot? You can use the paper clip icon in the INSERT section of the toolbar.

[Taimoor Khan Mehmand]

Did you mean the variables 'Vpu_5, Vpu_16, Vpu_17, Vpu_19'? . If yes, then how can I share that? Because they are stored in the MATLAB Workspace.

Or did you mean the SIMULINK model?

[Sanskar]

Can you share the plot which you are getting?

[Taimoor Khan Mehmand]

@Sanskar Yes sure, here it is.

[Aakash]

Can you share your variables 'Vpu_5, Vpu_16, Vpu_17, Vpu_19' which you told are stored in the MATLAB Workspace.

You can refer to this link on how to save your variables: https://www.mathworks.com/help/matlab/matlab_env/save-load-and-delete-workspace-variables.html. Then share as attachments

Answer 1

[Walter Roberson]

The code does displays the plot but in the legend first three Machines are shown with same red colour and the fourth machine i.e. Machine 19 is depicted by blue colour.

We can predict that Vpu_15.signals.values has three columns, so

plot(Vpu_15.time, Vpu_15.signals.values,'r')

is creating three lines, all of them colored red.

legend() matches to graphic objects not to the number of times that graphics functions are called. graphics functions can create multiple graphics objects in one call.

Work-around:

figure
h1 = plot(Vpu_15.time, Vpu_15.signals.values,'r');
hold on
h2 = plot(Vpu_16.time, Vpu_16.signals.values,'b');
hold on
h3 = plot(Vpu_17.time, Vpu_17.signals.values,'g');
hold on
h4 = plot(Vpu_19.time, Vpu_19.signals.values,'k');
hold off

xlabel('Time (s)')
ylabel('Voltage (pu)')
title('Machine Voltages')
legend('Machine 15', 'Machine 16', 'Machine 17', 'Machine 19')
legend([h1(1); h2(1); h3(1); h4(1)], 'TextColor', 'black')

[Taimoor Khan Mehmand]

@Walter Roberson

I ran your above code and result is attached here. Looks like still there is issue in the legend. Please see the plot result as attachment.

[Taimoor Khan Mehmand]

@Walter Roberson

If you look at the plot that I shared as an attachment, the blue colour is allocated to 'Machine 19', which is incorrect . Infact, 'Machine 19' must be depicted by 'black' color according to the short name assigned which is 'k'.

[Walter Roberson]

figure
h1 = plot(Vpu_15.time, Vpu_15.signals.values,'r');
hold on
h2 = plot(Vpu_16.time, Vpu_16.signals.values,'b');
hold on
h3 = plot(Vpu_17.time, Vpu_17.signals.values,'g');
hold on
h4 = plot(Vpu_19.time, Vpu_19.signals.values,'k');
hold off

xlabel('Time (s)')
ylabel('Voltage (pu)')
title('Machine Voltages')
legend([h1(1); h2(1); h3(1); h4(1)], {'Machine 15', 'Machine 16', 'Machine 17', 'Machine 19'}, 'TextColor', 'black');

[Taimoor Khan Mehmand]

@Walter Roberson

Thanks a lot. It worked.