how to set a line with different color

I want to set a line obj with different color on different parts. But the following code is not work.

pl=line(nan,nan,'color','b','userdata',[]);

x1=[1:500];

y1=sin(0.2*x1);

x2=[501:1000];

y2=sin(0.2*x2);

set(pl,'xdata',x1,'ydata',y1,'color','r','xdata',x2,'ydata',y2,'color','k');

Is that possible to set a line object with different color on different part?

Answer 1

[Guillaume]

No, it is not possible to have a single line object with segments of different colour. You have to have a new line object for each segment as per KSSV's example. Note that plot will return the array of line objects which you can pass as one variable to the other code that will act on it. You may have to modify slightly that other code so it can cope with a non-scalar object but it shouldn't be too arduous. e.g.:

x = linspace(0, 2*pi, 1000);
hlines = plot(reshape(x, [], 4), reshape(sin(x), [], 4))
[hlines.LineWidth] = deal(2);   %This is how to modify one of the property for all the lines at once
[hlines.LineStyle] = deal(':');

[yan zhang]

Thank you very much, you help me a lot!

[Cloud1995]

It is an awesome solution to my problem. Thanks so much!

Answer 2

[KSSV]

x1=[1:500];

y1=sin(0.2*x1);

x2=[501:1000];

y2=sin(0.2*x2);

figure
hold on
plot(x1,y1,'r')
plot(x2,y2,'b')
figure(2)
plot(x1,y1,'r',x2,y2,'b')

[Guillaume]

yan zhang's comment moved from answer to here(Please use comment on this answer rather than starting a new answer):

Thank you for your answer. But i want that a line object has different color, for i will use the line object in other codes. Is it possible to make a line object, and set different color on its different parts?

[KSSV]

YOu can do the following:

x1=[1:500];
y1=sin(0.2*x1);
x2=[501:1000];
y2=sin(0.2*x2);

line(x1,y1,'color','r') ;
line(x2,y2,'color','b') ;

[yan zhang]

Thanks a lot, the code will make two lines. Is it possible to combine the two line objects into a line obj?

[yan zhang]

Following codes are still not work.

pl=line(nan,nan,'color','b','userdata',[]);

x1=[1:500];

y1=sin(0.2*x1);

x2=[501:1000];

y2=sin(0.2*x2);

set(pl,'xdata',x1,'ydata',y1,'color','r');

set(pl,'xdata',x2,'ydata',y2,'color','k');

[KSSV]

When you use set the previous plot is over written. You can straight away use line as I have shown.

[yan zhang]

Thanks a lot. I should draw the line which will change every few seconds, and different colors represent different states. If a line obj can have different color, The code

   set(pl,'ydata',y);

will meet my request. I will try other ways to solve the problem.

Thanks again.