plot function legend is wrong.

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Ben Whitby
Ben Whitby on 20 Mar 2023
Commented: Ben Whitby on 20 Mar 2023
Hi All,
Can anybody give me some pointers on why the legend in the following plot is wrong. I use a loop to plot two variables, one is an array.
figure (55)
for i = 1:152
plot(t3,PowerAuts(:,:,i)); hold on;
end
hold on
plot(t3, MeanDailyPwr1,'color','k','LineWidth',4);
legend('MeanDailyPwr1','Orientation','horizontal')
grid on
ylim([0 40]);
yticks([0:5:40]);
xlim([t3(1) t3(end)])
ax.FontSize = 22;
xlabel('Time (hh:mm)','FontSize',24)
ylabel('Load Demand (kW)','FontSize',24)
title('Daily Load Demand','FontSize',28)
I want to display the variable MeanDailyPower1 in the legend but it is the wrong color at the moment.
  2 Comments
Antoni Garcia-Herreros
Antoni Garcia-Herreros on 20 Mar 2023
You may want to check here or here
You should reference your plot:
pMean=plot(t3, MeanDailyPwr1,'color','k','LineWidth',4);
l=legend(pMean,'MeanDailyPwr1','Orientation','horizontal');
Ben Whitby
Ben Whitby on 20 Mar 2023
I got it. Thank you.

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Answers (2)

Star Strider
Star Strider on 20 Mar 2023
The legend is probably picking up the first line plotted, that by default is blue.
Perhaps this —
figure (55)
for i = 1:152
plot(t3,PowerAuts(:,:,i)); hold on;
end
hold on
hpMDP = plot(t3, MeanDailyPwr1,'color','k','LineWidth',4);
legend(hpMDP, 'MeanDailyPwr1','Orientation','horizontal')
grid on
ylim([0 40]);
yticks([0:5:40]);
xlim([t3(1) t3(end)])
ax.FontSize = 22;
xlabel('Time (hh:mm)','FontSize',24)
ylabel('Load Demand (kW)','FontSize',24)
title('Daily Load Demand','FontSize',28)
Including the handle to the 'MeanDailyPower' plot specifies what the legend is to refer to.
.

Dave B
Dave B on 20 Mar 2023
Edited: Dave B on 20 Mar 2023
The legend is labeling the first line in the chart rather than the last one. An easy way to specify which line should be labeled in the legend is to grab the output from plot and pass that into the legend function
a = rand(10);
hold on
for i = 1:size(a,1)
plot(a(i,:))
end
aveline=plot(mean(a),'k','LineWidth',2);
legend(aveline,'The Average')

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