Last color on legend does not match last color on stem plot, after manually setting color in for loops.

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jdog
jdog 2024-6-25
评论： jdog 2024-6-26
Ran in:
This code generates stem plots for functions of number sequences. The last two plots require for loops to shift the sequences. The plot colors are hard coded in each loop to keep the same color. This works for the plots, but the legend shows the last two funcitons as both green when the last one should be purple. What might be causing this and is there a work-around?
x = [0,1,2,3,4,-4,-3,-2,-1,0];
y = [0,0,-1,0,1,0,-1,0,1,0,0];
longest_sequence = max(numel(x),numel(y));
figure(1)
hold on
stem(x,'LineWidth',2.0)
stem(5*x,'LineWidth',2.0)
stem(y,'LineWidth',2.0)
for n = 2:9
stem(n-1,y(n+1),'LineWidth',2.0, 'Color','#77AC30')
end
for n = 2:9
stem(n-1,-2*x(n-1)+3*y(n+2),'LineWidth',2.0,'Color','#7E2F8E')
end
hold off
title('Problem 1')
xlim([0 longest_sequence+1])
xticks(0:1:11)
yticks(-20:1:20)
xlabel('Time')
ylabel('Amplitude')
set(gca,'FontWeight','bold')
legend('x','5x','y','y(n+1)','-2x(n-1)+3y(n+2)')

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采纳的回答

Walter Roberson
Walter Roberson 2024-6-25
for n = 2:9
stem(n-1,y(n+1),'LineWidth',2.0, 'Color','#77AC30')
end
That generates multiple plot objects, each with green color.
legend('x','5x','y','y(n+1)','-2x(n-1)+3y(n+2)')
That assigns legends to consecutive plot objects.
Your mistake was in thinking that the stem() within the for loop would all get grouped into the same legend.
  2 个评论
Walter Roberson
Walter Roberson 2024-6-25
Ran in:
x = [0,1,2,3,4,-4,-3,-2,-1,0];
y = [0,0,-1,0,1,0,-1,0,1,0,0];
longest_sequence = max(numel(x),numel(y));
figure(1)
hold on
H1 = stem(x,'LineWidth',2.0);
H2 = stem(5*x,'LineWidth',2.0);
H3 = stem(y,'LineWidth',2.0);
for n = 2:9
H4 = stem(n-1,y(n+1),'LineWidth',2.0, 'Color','#77AC30');
end
for n = 2:9
H5 = stem(n-1,-2*x(n-1)+3*y(n+2),'LineWidth',2.0,'Color','#7E2F8E');
end
hold off
title('Problem 1')
xlim([0 longest_sequence+1])
xticks(0:1:11)
yticks(-20:1:20)
xlabel('Time')
ylabel('Amplitude')
set(gca,'FontWeight','bold')
legend([H1, H2, H3, H4, H5], {'x','5x','y','y(n+1)','-2x(n-1)+3y(n+2)'})

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