How to delete rows based on value of first column in matrix-CodePudding

I have a 3D matrix xyposframe and I would like to delete all rows in that matrix where the first column has a number below 150 or over 326. I tried the following but this didn't give me the desired result:

indexbelow = xyposframe(:, 1) < 150;
indexabove = xyposframe(:, 1) > 326;
xyposframe(indexbelow, :) = [];
xyposframe(indexabove, :) = [];

How can I delete those rows?

CodePudding user response：

The problem is that both indexbelow and indexabove are of size n -by- 1, i.e. column vectors with as much elements as there are rows in xyposframe. With xyposframe(indexbelow, :) = []; you remove a number of rows, thus making xyposframe have less than n rows, resulting in an error when you try to call xyposframe(indexabove, :) = [];, since you're attempting to index less than n elements with a total of n indices.

Possible solutions are to split the operation into two parts, or combine them in a single logical statement:

% First one, then the other
indexbelow = xyposframe(:, 1) < 150;
xyposframe(indexbelow, :) = [];
indexabove = xyposframe(:, 1) > 326;
xyposframe(indexabove, :) = [];

% Combine using logical AND
indexbelow = xyposframe(:, 1) < 150;
indexabove = xyposframe(:, 1) > 326;
xyposframe(indexbelow & indexabove, :) = [];

% Or put everything in a single indexing line using logical OR
xyposframe(xyposframe(:,1)<150 | xyposframe(:,1) > 326) = [];