extracting x,y data from certain time points in matrix?

Hello!

I have the txt file that looks as follows:

x y

.001 1
.002 3
.5   5
5    10
6    11
7    12
8    13
9    15
10   17
11   20

Where the first column is time and the second column is a changing value y.

I want to extract all the x,y values where x<=10 and x>= 5, e.g.

5    10
6    11
7    12
8    13
9    15
10   17

As of now the code I am using is (where srtm is the first code box above):

x = find(srtm(:, 1)> 5 & srtm(:,1) < 20)

and that just gives me the corresponding column numbers (4, 5, 6, 7, 8, 9), but not at x values.

My question is:

1) how to I extract the x, y coordinates from a matrix where x=> number1, x=<number2?

Thanks so much for all of your help!

Answer 1

[Image Analyst]

Instead of

x = find(srtm(:, 1)> 5 & srtm(:,1) < 20)

to do masking from 5 to 10 inclusive, you need to change x to indexes, 20 to 10, and use <= and <=

x = srtm(:, 1);
y = srtm(:, 2);
% Find linear indexes in the range [5, 10].
indexes = find(x >= 5 & x <= 10) % Or could use logical indexes, like: indexes = x >= 5 & x <= 10
% Extract values in that range ONLY.
xm = x(indexes);
ym = y(indexes);
plot(xm, yb, 'b.-', 'LineWidth', 2, 'MarkerSize', 20);

[nines]

thank you so much! this worked perfectly! so so grateful!