Easy Noob Indexing Question

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Richard Keniuk
Richard Keniuk on 19 Dec 2020
Commented: Richard Keniuk on 27 Dec 2020
I'm sure this answer is looming in front of me but I am missing it somehow. I have an array
A = [0 0;1 -1; -1 1;1 -1; -1 1];
B = [2 -2; -2 2;2 -2; -2 2;2 -2; -2 2;2 -2;0 0];
and I'm concatenating these two in the vertical direction but I only want rows 4:7 of my concatenated output.
I am doing this in two steps.
C = cat(1,A,B); % or some other calculation of vectors A and B
C = C(4:7,:);
How can I reduce this to one command by directly indexing the equation of "cat(1,A,B)" directly into C?
I know that I could do this by C = cat(1,A(end-1:end,:),B(1:2,:)). A and B are of variable length and I only want C to hold the concatenation +/-2 indices vertically. Is there another way in a single line?
Image Analyst
Image Analyst on 19 Dec 2020
My programs have thousands of lines of code. Why does yours have to be just one line of code instead of 2? Your last way of using end will work for variable sizes arrays.

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Accepted Answer

Rishabh Mishra
Rishabh Mishra on 23 Dec 2020
Use the code below for resolving your issue:
This is the simplest way to code the solution for the issue you are facing.
Hope this helps !
  1 Comment
Richard Keniuk
Richard Keniuk on 27 Dec 2020
I guess I already had this to the "cleanest" implementation. I thought maybe I was missing something here.
Thanks for your help.

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