Plotting different color points based on array values

I have an array and I want to plot it applying different colors depending on the values. If the value to be plotted is below a threshol the color is green, if above it should be red. All data should be connected by straight line.

Whit the code here I can only display values below the threshold.

How can I display all the values?

length1=length(DE);

for i=1:length(DE)

if DE(i)>=5

color='or';

else

color='og';

plot(data.Name_1(i),DE(i),color)

end

hold on

end

Answer 1

[William Rose]

@Elena Zucchetti,

One way:

x=1:100;
N=length(x);
DE=10*rand(1,N);
c=zeros(N,3); %allocate colors
for i=1:N, if DE(i)>5, c(i,:)=[1,0,0]; else c(i,:)=[0,1,0]; end, end
subplot(211); scatter(x,DE,50,c,'filled'); hold on
plot(x,DE,'-k'); hold off  %add line connecting the points, as you requested

Another way:

clear
x=1:100;
DE=10*rand(size(x));
subplot(212); scatter(x(DE<5),DE(DE<5),'g','filled');
hold on
scatter(x(DE>=5),DE(DE>=5),'r','filled');
plot(x,DE,'-k');  %add straight lines between points

Try it. Good luck.

Answer 2

[Les Beckham]

x = linspace(0, 10);
y = sin(x); % test data
yhi = y;
ylo = y;
threshold = 0.5;
idxlo = y <= threshold;
idxhi = y > threshold;
yhi(idxlo) = nan;
ylo(idxhi) = nan;
plot(x, yhi, 'ro-', x, ylo, 'go-')
grid on

Answer 3

[Voss]

data = struct('Name_1',randperm(50));
DE = 2.5+5*rand(1,50);
threshold = 5;

[~,idx] = sort(data.Name_1);
x = data.Name_1(idx);
y = DE(idx);
xy = [x(:) y(:)];

direction = diff(xy(:,2) > threshold);
do_interp_up = [direction == 1; false];
do_interp_down = [direction == -1; false];
do_interp = do_interp_up | do_interp_down;
N = size(xy,1);
new_xy = NaN(N+3*nnz(do_interp),2);
jj = 1;
for ii = 1:N
    new_xy(jj,:) = xy(ii,:);
    if do_interp(ii)
        new_xy(jj+[1 3],1) = interp1(xy(ii+[0 1],2),xy(ii+[0 1],1),threshold);
        new_xy(jj+2,2) = threshold;
        if do_interp_up(ii)
            new_xy(jj+[1 3],2) = threshold+[-1 1]*eps(threshold);
        else
            new_xy(jj+[1 3],2) = threshold+[1 -1]*eps(threshold);
        end
        jj = jj+3;
    end
    jj = jj+1;
end

low_idx = new_xy(:,2) <= threshold;
high_idx = new_xy(:,2) >= threshold;

hold on
plot(new_xy(low_idx,1),new_xy(low_idx,2),'g')
plot(new_xy(high_idx,1),new_xy(high_idx,2),'r')