Specify wich values appear on a plot legend

I'm plotting in a for loop a series of signals and additionally lines to separate segments in the plot. I want to add a Legend for each of the signal but when I add the legend it adds the lines too and Im not really sure how to take the lines out of the Legend.

My code is:

for j=1:8
  figure(j)
  for i=1:6
    plot(f(j,:,i),cxy(j,:,i))
    hold on
    xlim([0 45])
    line ([4,4],[0, 1],'Color','red','LineStyle','--')  % Cada linea separa las bandas de energia para ver la coherencia entre bandas
    line ([8,8],[0, 1],'Color','red','LineStyle','--')
    line ([13,13],[0, 1],'Color','red','LineStyle','--')
    line ([30,30],[0, 1],'Color','red','LineStyle','--')
    % Here the legend should appear only for the plots not for the lines
    legend('Signal 1','Signal 2','Signal 3','Signal 4','Signal 5', 'Signal 6')
  end
end

My result is the plot I attach. I've searched arround how to solve this but nothing is working.

Thanks in advanced for the help and sorry for the basic question.

[KALYAN ACHARJYA]

"how to take the lines out of the Legend?"

Which lines are you talking?

Are these lines within legend dashed colors lines?

[Juan Sanchez]

Yes sorry if I didnt explain well, the lines:

if true
  line ([4,4],[0, 1],'Color','red','LineStyle','--')  % Cada linea separa las bandas de energia para ver la coherencia entre bandas
  line ([8,8],[0, 1],'Color','red','LineStyle','--')
  line ([13,13],[0, 1],'Color','red','LineStyle','--')
  line ([30,30],[0, 1],'Color','red','LineStyle','--')
end

These dotted lines appear in the legend

Answer 1

[dpb]

Use the handles of the lines you wish to add legends to...

nFig=8;                     % set the numbers via variables
nLin=6;                     % instead of using "magic" numbers...
hL=gobjects(nFig,nLin);     % preallocate for the line handles
for j=1:nFig
  figure(j)
  for i=1:nLin
    hL(j,i)=plot(f(j,:,i),cxy(j,:,i));  % plot the line, save the line handle for it...
    hold on
    xlim([0 45])
    line ([4,4],[0, 1],'Color','red','LineStyle','--')  % Cada linea separa las bandas de energia para ver la coherencia entre bandas
    line ([8,8],[0, 1],'Color','red','LineStyle','--')
    line ([13,13],[0, 1],'Color','red','LineStyle','--')
    line ([30,30],[0, 1],'Color','red','LineStyle','--')
    % Here the legend should appear only for the plots not for the lines
  end
  % Add legend after the lines are drawn using the handles of those wanted to show only
  legend(hL(j,:),{'Signal 1','Signal 2','Signal 3','Signal 4','Signal 5', 'Signal 6'})
end

One could also build the legend text dynamically to match the loop indices instead of hardcoding...

[Juan Sanchez]

Sir, most appreciated. The magic numbers correspond to the dimensions of the data but anyway you are right. As for the code in:

legend(hL(i,:).... should be replaced by a j since they are 6 plots.

Anyway Thank you for the clear explanation! Most appreciated.

[dpb]

You're right, got the loop indices reversed...I'll make the correction, thanks.

If don't code with "magic numbers" as general rule it makes modifying/using code for other purposes much easier or makes the given code useful if the present data sizes change for any reason.

I wasn't really suggesting to just move the constants to explicit variables; I just used that as a shortcut/prompt, what I really meant was to do something like

[nFig,nLin]=size(cxy);

THEN, if you get a dataset for some reason that isn't exactly 8x6 you still don't have to do anything but run the code to process it.

It's just a good habit to develop.