plot a certain x,y values from a large matrix

hi,

i have a 4000rows(with x value from 1:4000) and 2 column (of y values) matrix. How can i plot x&y with, say, taking x value from x > 500 and x<2500 and their corresponding y values?

thank you very much.

Answer 1

[Lessmann]

You can use the colon operator to select a subset of your vector, like

plot(x(500:2500),y(500:2500))

[smo]

Hi, thanks for that. I didn't make myself clear enough, I actually meant i don't know the index of x. (which means x are a set of numbers not in orders).

But I have did a small test myself and found the answer: first index x-values and then use the x and y value only for that index. I am putting my answer here incase it can help someone else.

for example:

x = [1:10];

y = [11:20];

idx = find (x>3 & x <7);

x_new = x(idx);

y_new = y(idx);

plot (x_new, y_new, '-o')

Answer 2

[Star Strider]

This works:

x = randi(4000, 1, 100);            % Create Data
y = randi(99,   2, 100);

xp = x(x>500 & x<2500);
yp = y(:,(x>500 & x<2500));

figure(1)
plot(xp, yp, 'bp')
grid