Plotting Legend in a For Loop

Question

Mridul Garg 2016-6-28

0
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https://ww2.mathworks.cn/matlabcentral/answers/292774-plotting-legend-in-a-for-loop

评论： dpb 2016-6-30

I am trying to plot multiple lines on a plot, and want my legend to reflect those line styles as well as colors. I am using the following for loop-

for i=2:5
  sigma_level=i; hold on;
  h1=plot(x1,[meanf-sigma_level*stdf meanf-sigma_level*stdf],'Color',rand(1,3));
  legendInfo{i-1}=[num2str(i),'\sigma'];
end;
legend(legendInfo)

My issue is that the legend does not reflect the lines plotted, because I'm not using the h1 variable to identify it in the legendInfo. If I use

legendInfo{i-1}=[h1,num2str(i),'\sigma']

I get the following error-

Error using matlab.graphics.chart.primitive.Line/horzcat
Conversion to matlab.graphics.chart.primitive.Line from char is not possible.
Error in test (line 33)
legendInfo{i-1}=[h1,num2str(i),'\sigma'];

What is the possible solution to fix this?

Thanks!

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Answer 1

dpb 2016-6-28

1
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在 MATLAB Online 中打开

plot returns a line handle; you're overwriting the previous handles on the subsequent passes thru the loop...

j=0;  % accumulator; not sure why ran loop 2:5??
for i=2:5
  j=j+1;
  sigma_level=i;
  h(j)=plot(x1,[meanf-sigma_level*stdf meanf-sigma_level*stdf],'Color',rand(1,3));
  if j==1, hold on, end  % only set hold after first plot...
  legendInfo{j}=[num2str(i),'\sigma'];
end;
legend(h,legendInfo)