Plotting vectors making chart

I have a 25x5 matrix, M, I want to obtain values from the third column which are >1.5, <0.5, and the remaining values of the third column. I would ideally like to plot them in different colors on the same graph. so far I have got this but I don't think its correct, N=M(:,3) if N>1.5 plot(N, 'r') hold on if N<0.5 plot(N, 'b') hold on plot(N, 'g') end

Thanks

Answer 1

[Voss]

Maybe something like this?

M = randn(100,5); % some random data for demo

N = M(:,3);

idx = find(N > 1.5);
plot(idx, N(idx), 'r.')

hold on

idx = find(N < 0.5);
plot(idx, N(idx), 'b.')

idx = find(N >= 0.5 & N <= 1.5);
plot(idx, N(idx), 'g.')

[Voss]

M = randn(100,5); % some random data for demo
x = 1:size(M,1);

N = M(:,3);

idx_big = N > 1.5;
plot(x(idx_big), N(idx_big), 'r.')

hold on

idx_small = N < 0.5;
plot(x(idx_small), N(idx_small), 'b.')

idx_middle = ~idx_big & ~idx_small;
plot(x(idx_middle), N(idx_middle), 'g.')

[Voss]

@ac737: I'm going to share the message you sent me, clarifying the problem:

"... My matrix is [ redacted at OP's request - Voss ]

Each of the columns represent time(hrs) and the rows represent microbial activity. I want to produce a colour coded plot of the time course of activity of each gene so that any gene with:

activity at 3hrs (3rd column) > 1.5 is drawn in red

activity at 3hrs (3rd column) < 0.5 is drawn in blue

activity at 3 hrs (3rd column) otherwise drawn in green

I know I can plot a vector say a by

plot(a, 'r')

hold on

plot(a, 'b')

hold on

plot(a, 'g') etc.

Do I have to plot this in a loop 25 times to get the desired result?

My final figure should all start at 1, which makes me think I am supposed to plot for all microbes, sorry if this doesn't make sense, thank you for any help"

My response:

You can use a loop, and the code would not be much different from what you had in your original question:

M = [
    %redacted
    ];

N = M(:,3);

figure()
hold on

for ii = 1:numel(N)
    if N(ii) > 1.5
        plot(M(ii,:), 'r')
    elseif N(ii) < 0.5
        plot(M(ii,:), 'b')
    else
        plot(M(ii,:), 'g')
    end
end

Another way, using logical indexing instead of a loop, would be:

N = M(:,3);

figure()
hold on

idx_big = N > 1.5;
plot(M(idx_big,:).', 'r')

idx_small = N < 0.5;
plot(M(idx_small,:).', 'b')

idx_middle = ~idx_big & ~idx_small;
plot(M(idx_middle,:).', 'g')

[Vc27]

Thank you!

[Voss]

You're welcome!