It's a bit unclear what you mean by the question. You could divide the set of data into segments using logical indexing. For example
x = 0:0.1:2*pi;
y = sin(x);
s{1} = x > pi;
s{2} = x <= pi;
Now you can plot the first and second part separately.
plot(x(s{1}),y(s{1}),'r',...
x(s{2}),y(s{2}),'b')
It's also trivial to access the different segments in a loop.
