Mark specific values on a plot!

Hi consider the following plot:

x=1:100;
 y=600+(1400-600).*rand(100,1);
 plot(x,y)

How can I mark the y values between 900 and 1100? Thanks!

[Rik]

With hold on and plotting a line over it with an increased line width you could emphasize a certain range.

Answer 1

[Birdman]

Additional to your code, use the following lines:

yMark=zeros(1,100);%preallocation for speed
for i=1:1:length(y)
if(y(i)>=900 && y(i)<=1100)
yMark(i)=y(i);
end
end
plot(x,yMark,'->')

[Rik]

You can vectorize the loop:

yMark=zeros(1,100);
yMark(y>=900 & y<=1100)=y(y>=900 & y<=1100)

Be aware that this code (both mine and the loop) will result in zero values outside the wanted range. You can fix this by either initializing to a NaN (just replace zeros with NaN), or shortening x the same way as you shorten y:

yMark=y(y>=900 & y<=1100)
xMark=x(y>=900 & y<=1100)

[Birdman]

Yes you are right. It will make the code more efficient. I just wanted to mark those values on the plot. Thank you for your attention.

Answer 2

[Hellen Nassuna]

x=1:100;
 y=600+(1400-600).*rand(100,1);
 plot(x,y)
 hold on;
 yMark=NaN(1,100);%preallocation for speed
for i=1:1:length(y)
if(y(i)>=900 && y(i)<=1100)
yMark(i)=y(i);
end
end
plot(x,yMark,'->')

hold off

    if true
      % code
    end