Selecting Every Other Element in a Matrix

How can I select every other element in a matrix, such as A=[1 2 8 7 6 5 4 6]?

Answer 1

[Star Strider]

I’m not certain what you want, so I’ll venture two possibilities:

A=[1 2 8 7 6 5 4 6];
Aodd = A(1:2:end);          % Odd-Indexed Elements
Aeven = A(2:2:end);         % Even-Indexed Elements

[Dewey Phillips]

this worked for me

[Aditya Kansal]

i want to do the same for a 2-D array, how can i achieve that?

[Nitai Fingerhut]

A=[1 2 8; 7 6 5; 4 6 9];

A= A(:);

Aodd = A(1:2:end); % Odd-Indexed Elements

Aeven = A(2:2:end); % Even-Indexed Elements

at the end use reshpae to make it 2D again

[Stephen23]

"i want to do the same for a 2-D array, how can i achieve that?"

A(1:2:end,:) % odd rows
A(2:2:end,:) % even rows
A(:,1:2:end) % odd columns
A(:,2:2:end) % even columns

Very basic concepts, such as how to use indexing, are explained in the introductory tutorials:

https://www.mathworks.com/help/matlab/getting-started-with-matlab.html

[Khyati Jain]

How do you do this if it is a complex vector?

[Atas Jyoti Kaibarta]

only for real number

[Star Strider]

It should work the same way for complex vectors, however the problem with that is that it could select only one of a complex pair. One way to correct for that would be to use the conj function to complete the pair after selecting them, then use the cplxpair function.

You would need to decide whether you wanted to select from complex vectors to begin with. The problems that could cause might not be worth the efffort.

Answer 2

[prashanth GT]

function y = everyOther(x)

y = x(1:2:length(x));

end