Legend in Matlab in for Loop
I Have a for Loop That Looks Somewhat Like These: Rowtoplot =2; Num=2; Swatchtoplots=[2 3]; Datatograph=Rand(168,97); [Rowsdata, Colsdata]=Size(Datatograph)...
I have a for loop that looks somewhat like these:
RowToPlot =2;
Num=2;
SwatchToPlots=[2 3];
DataToGraph=rand(168,97);
[RowsData,ColsData]=size(DataToGraph);
x=1:RowsData;
figure
for idx=1:Num
SwatchToPlot=SwatchToPlots(1,idx);
if RowToPlot==1
if SwatchToPlot==1
plot(x,DataToGraph(:,22:25));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
elseif SwatchToPlot==2
plot(x,DataToGraph(:,46:49));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
elseif SwatchToPlot==3
plot(x,DataToGraph(:,70:73));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
elseif SwatchToPlot==4
plot(x,DataToGraph(:,94:97));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
end
elseif RowToPlot==2
if SwatchToPlot==1
plot(x,DataToGraph(:,18:21));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
elseif SwatchToPlot==2
plot(x,DataToGraph(:,42:45));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
elseif SwatchToPlot==3
plot(x,DataToGraph(:,66:69));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
elseif SwatchToPlot==4
plot(x,DataToGraph(:,90:93));hold on;
legend('ex1', 'ex2', 'ex3', 'ex4');
end
end
end
Each plot line plots 4 lines in the y axis, and depending on the value in Num, the for loop could repeat and more lines could be plotted. If the for loop happens only one time, then I can easily add a legend using the legend() function. However, if the for loop happens more than once, the new legend does not append to the existing legend. How can I append the legend to the already existing legend, instead of just replacing it?
*Note: I've read similar questions but can't still make it work given that I'm plotting four y lines using a single plot() function.
1 Answer
It is best to always provide a Minimum Reproducible Example. Since that was not provided, I wrote a dummy script underlying the usage of legend command within loops.
close all; clc;
t = 0:0.01:10; % time vec
w = 1; % fixed frequency in rad
arrayLimiter = length(t);
% create some sine signals with phase delay for demo purposes
signal1 = zeros(arrayLimiter, 1);
signal2 = zeros(arrayLimiter, 1);
signal3 = zeros(arrayLimiter, 1);
for i = 1:arrayLimiter
signal1(i) = sin(2*pi*w*t(i) + 0);
signal2(i) = sin(2*pi*w*t(i) + 30);
signal3(i) = sin(2*pi*w*t(i) + 60);
end
figure;
hold on; grid on; set(gcf, 'color', 'w'), ylim([-2 2]),
for i = 1:3
plot(t, signalArr(:, i), 'DisplayName', ['Singal ', num2str(i)]),
end
legend show,
Which gives the following output: You can programmatically add as many legend entries along with signals, using the "DisplayName" functionality of the plot function. Let me know if anything is unclear.
Alexander Ross has covered the video game industry for a decade, writing deep dives on game design, esports tournaments, VR developments, and gaming culture.
