how can i save the even index to a matrix 2:5 using for loop

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Ali ALATAWI on 6 Nov 2021
Edited: Chris on 6 Nov 2021
i print the even position in matrix z but the qausition is to save the output of the loop which is even index into a other matrix 2:5 using for loop . this is the code to produce an even endex
clear all
clc
z=randi([1 10],5,10)
for i=1:5
if(mod(i,2)==0)
for j=1:10
if(mod(j,2)==0)
fprintf('even index:%d\n',z(i,j))
end
end
end
end

Sargondjani on 6 Nov 2021
Edited: Sargondjani on 6 Nov 2021
I think you want something like this:
(which you could speed up by pre-allocating MAT=NaN(2,5))
cnt_rows = 0;
cnt_cols = 0;
for i=1:5
if(mod(i,2)==0)
cnt_rows = cnt_rows+1;
for j=1:10
if(mod(j,2)==0)
cnt_cols = cnt_cols+1;
MAT(cnt_rows,cnt_cols) = z(i,j);
end
end
end
end

Chris on 6 Nov 2021
Edited: Chris on 6 Nov 2021
z=randi([1 10],5,10)
z = 5×10
10 3 6 8 4 7 10 6 2 7 8 9 7 1 1 3 2 3 4 1 6 9 3 6 8 8 2 5 2 3 7 10 9 10 8 6 2 6 7 1 6 6 8 4 6 4 2 4 10 10
newmatrix = [];
for i=1:5
if(mod(i,2)==0)
for j=1:10
if(mod(j,2)==0)
% fprintf('even index:%d\n',z(i,j))
newmatrix(end+1) = z(i,j);
end
end
end
end
newmatrix = reshape(newmatrix,5,2)'
newmatrix = 2×5
9 1 3 3 1 10 10 6 6 1
Alternatively, move down the columns in the inner loop. Then a 2x5 matrix would fill up naturally, retaining the orientation of the larger matrix.
z=randi([1 10],5,10)
newmatrix = zeros(2,5);
idx = 1;
for j=1:10
if(mod(j,2)==0)
for i=1:5
if(mod(i,2)==0)
% fprintf('even index:%d\n',z(i,j))
newmatrix(idx) = z(i,j);
idx = idx+1;
end
end
end
end
newmatrix

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