Cropping a range of Coordinates from a bigger data set

I have an x-y coordinates data set measuring [0 2000 0 4000]. I wish to extract the coordinates in the range [500 1500 0 1000]. How do I do this? Thanks.

Answer 1

[Image Analyst]

John: Thanks for the improved explanation. Try this:

% Generate some sample data.
xyCoords = 4000 * rand(50, 2)
% Now determine when x is in range.
x_in_range = xyCoords(:,1) >= 500 & xyCoords(:,1) <= 1500
% Now determine when y is in range.
y_in_range = xyCoords(:,2) >= 0 & xyCoords(:,2) <= 1000
% Now determine when both x and y are in range.
both_in_range = x_in_range & y_in_range;
% Now extract those rows where both are in range.
out = xyCoords(both_in_range, :)

[John]

Thanks

Answer 2

[Image Analyst]

I"m not sure what measuring [0 2000 0 4000]" means. This is very imprecisely worded. I'm guessing that you have a 1-dimensional array where you have the 2001 x coordinates first, followed by 4001 y coordinates. I'm not sure why you have more y coordinates than x coordinates though. If so, I'd do this:

index1 = 500;
index2 = 1500;
xCoordinates = xy(index1:index2);
index1 = 2001 + 1; % Index of the first y coordinate.
index2 = 2001+1000; % Index of the 1000th y coordinate.
yCoordinates = xy(index1:index2);

If you mean something different then you'd need to explain better what you want.

[John]

The coordinates are the x-y positions of trees in a given area [minX=0 maxX=2000 minY=0 maxY=4000]. I wish to extract the coordinates of trees in [minX=500 maxX=1500 minY=0 maxY=1000]

Answer 3

[Walter Roberson]

XY( XY(:,1) >= 500 & XY(:,1) <= 1500, XY(:,2) >= 0 & XY(:,2) <= 1000)

[John]

I've tried this but I get 'Index exceeds matrix dimensions' error :(