Difficulty setting legend dataset colour

Hello,

I am having some difficulty with my legend. I keep getting the following error: 'Subset must be a vector of graphics objects.'

My current code is:

figure;
    h1 = plot((conTime(1:15,[1:3,5:6,8:end])), conBw(1:15,[1:3,5:6,8:end])); hold on;
    h2 = plot((b9Time(1:15,3:end)), b9Bw(1:15,3:end)); hold on;
    set(h1, 'Color', 'r');
    set(h2, 'Color', 'b');
    xlabel('Time (days)', 'FontSize', 12);
    ylabel('Body Weight (g)', 'FontSize', 12);
    xlim([1,50]);
    xticks(0:5:50);
    legend([h1, h2], 'Control', 'Intervention', 'location', 'southeast', 'FontSize', 11);
    legend box off;
   

On the other hand, when I set my legend using the following code, both my 'Control' and 'Intervention' appear with red lines, rather than red and blue (as I have set them):

    legend('Control', 'Intervention', 'location', 'southeast', 'FontSize', 11);

Your feedback is greatly appreciated.

Many thanks.

[Fangjun Jiang]

what version? no problem in R2019b.

[NA]

I'm using Matlab version R2019b

[Fangjun Jiang]

close all existing figures. I ran this and no errors.

figure;
h1 = plot(1:10); hold on;
h2 = plot(10:-1:0); hold on;
set(h1, 'Color', 'r');
set(h2, 'Color', 'b');
xlabel('Time (days)', 'FontSize', 12);
ylabel('Body Weight (g)', 'FontSize', 12);
xlim([1,50]);
xticks(0:5:50);
legend([h1, h2], 'Control', 'Intervention', 'location', 'southeast', 'FontSize', 11);
legend box off;

[NA]

Your code works as you have written it. Except, when I use it on my existing code I still get the error: 'Subset must be a vector of graphics objects.'

I wonder if it is because I have selected specific columns to plot per dataset?

[Fangjun Jiang]

check the value of h1 and h2. I could have this error if plot multiple lines in h1

Error using horzcat
Dimensions of arrays being concatenated are not consistent.
Error in Untitled (line 11)
legend([h1, h2], 'Control', 'Intervention', 'location', 'southeast', 'FontSize', 11);

[NA]

I just solved it. In my original code, the object handles that I used in my legend (h1, h2) would refer to each set of datapoints per group i.e. I have 14 subjects per group). So essentially, when I 'show' my legend I would get 28 datasets in my legend (14 from each group). What I did to overcome this was to specify the first dataset per group (h1(1), (h2(2)) and voila, problem solved.

legend([h1(1), h2(1)], 'Control', 'Intervention', 'location', 'southeast', 'FontSize', 11);

Anyway, thank you for taking the time to help.

[Fangjun Jiang]

I see. I could duplicate your error now. The result of [h1, h2] could be a vector but can't be a matrix. The error message is poorly constructed.

[NA]

Precisely. I'm glad it is sorted now, and will know what to do next time. Thanks again :)