How do i prevent previous legend entries to get erased

i have a code which is used to analyse some raw data data and compare the results of many(unknown number) of tests. for this my code first starts like this

    prompt='how many files do you wish to analyse? ';
    prompt1='what is the name of the test?  ';
    prompt2='what is the name of the file? ';

    n=input(prompt);

    for i=1:n
        name(i,:)=input(prompt1,'s');
        filename(i,:)=input(prompt2);
    end
    for i=1:n
        a(:,:,i)=ftp_75_2(filename(i,:));
        for j=1:18
            figure(j)
            legend(name(i,:));
        end
    end

the trouble is every time a new legend gets added the old one gets removed. can someone help me. I have seen some solutions online but they all require the person who runs the code to create a specific label command or to know the number of files which will be in the legend rather than take an input from the user.

I am creating this code to give prompts since the people who are to use this will have little to no matlab knowledge

Answer 1

[Joseph Cheng]

Off the top of my head it is not part of the legend function. However it doesn't stop us from modifying what is already there.

for ind = 1:3
    x = randi(10,10,5);
    figure(ind),plot(x);
     hleg(ind) = legend('toggle');
end

names = {'line 1','line 2','line 3','line 4','line 5'};
for ind = 1:size(x,2)
    for jnd = 1:3
       legStr = get(hleg(jnd),'string');
       legStr(ind) = names(ind);
       set(hleg(jnd),'string',legStr);
    end
end

[SamwiseGamgee]

The number of files which shall be processed through my code is a user input and hence the number of loops and legend entries cannot be fixed.

[Joseph Cheng]

and? if you played around with the code you can see how to add items using set or legend. I have no idea what your ftp function does so i assumed it added plots to the line but the legend markings were done after the plots were generated. So.... here is a modification of the things i did before.

clc
clear all
close all;
hfig = figure(1);hold on;
n=1;
while 1
    answer = questdlg('add another plot?', ...
                         'add plot', ...
                         'yes', 'no','yes');
    switch answer
        case 'yes'
            hleg = legend;
            plot(randi(10,1,10))
            hlegstr = get(hleg,'string');
            hlegstr{n} = ['plotnum ' num2str(n)];
            legend(hlegstr)
            n=n+1;
        case  'no'
            break
    end
end