Easy Noob Indexing Question

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Richard Keniuk 2020-12-19

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https://ww2.mathworks.cn/matlabcentral/answers/698085-easy-noob-indexing-question

评论： Richard Keniuk 2020-12-27

采纳的回答： Rishabh Mishra

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];

and

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?

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KALYAN ACHARJYA 2020-12-19

在 MATLAB Online 中打开

Is there any issue with that, simplest and easiest?

C=[A;B];
C=C(4:7,:)

Image Analyst 2020-12-19

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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