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

Question

Ali ALATAWI 2021-11-6

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1580269-how-can-i-save-the-even-index-to-a-matrix-2-5-using-for-loop

编辑： Chris 2021-11-6

Capture.PNG

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

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Answer 1

Sargondjani 2021-11-6

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https://ww2.mathworks.cn/matlabcentral/answers/1580269-how-can-i-save-the-even-index-to-a-matrix-2-5-using-for-loop#answer_825129

编辑：Sargondjani 2021-11-6

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

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Answer 2

Chris 2021-11-6

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1580269-how-can-i-save-the-even-index-to-a-matrix-2-5-using-for-loop#answer_825134

编辑：Chris 2021-11-6

在 MATLAB Online 中打开

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