How to use nested loop to produce the row and columns like that

Question

Shuoze Xu 2022-3-22

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1677419-how-to-use-nested-loop-to-produce-the-row-and-columns-like-that

评论： Mathieu NOE 2022-3-22

采纳的回答： Mathieu NOE

Given a 2D array, called A, of size 5 x 5,

Sample Output: Given A = [2,4,8,7,3;2,2,3,4,3;5,5,4,2,7;8,2,7,3,9;1,2,3,4,5];

output:

2 4 8 7 3

2 2 3

5 5 7

8 2 7 3 9

1 2 3 4 5

% My code

A = [2,4,8,7,3;2,2,3,4,3;5,5,4,2,7;8,2,7,3,9;1,2,3,4,5];

rows = size(A,1) % the number of rows in A

columns = size(A,2) % the number of columns in A

B = [];

for row = 1:rows

for column = 1:columns

if (row == 2 || row == 3)

if (column == 3 || column == 4)

B = [B A(i)]

end

disp(B);

My code is wrong i thought

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Answer 1

Mathieu NOE 2022-3-22

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https://ww2.mathworks.cn/matlabcentral/answers/1677419-how-to-use-nested-loop-to-produce-the-row-and-columns-like-that#answer_923824

在 MATLAB Online 中打开

hello

seems to me B is simply A but rows 2 and 3 for columns 3 and 4 are empty (filled with NaN)

code :

 A = [2,4,8,7,3;2,2,3,4,3;5,5,4,2,7;8,2,7,3,9;1,2,3,4,5];
 B = A;
 B(2:3,3:4) = NaN;

results :

A =

2 4 8 7 3

2 2 3 4 3

5 5 4 2 7

8 2 7 3 9

1 2 3 4 5

B =

2 4 8 7 3

2 2 NaN NaN 3

5 5 NaN NaN 7

8 2 7 3 9

1 2 3 4 5

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Shuoze Xu 2022-3-22

Wow, it works.

Thank you so much

Mathieu NOE 2022-3-22

My pleasure !

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Answer 2

Arif Hoq 2022-3-22

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https://ww2.mathworks.cn/matlabcentral/answers/1677419-how-to-use-nested-loop-to-produce-the-row-and-columns-like-that#answer_923819

在 MATLAB Online 中打开

you did not clear your expection. you can try this

A = [2,4,8,7,3;2,2,3,4,3;5,5,4,2,7;8,2,7,3,9;1,2,3,4,5];
rows = size(A,1); % the number of rows in A
columns = size(A,2); % the number of columns in A
B = [];
for row = 1:rows
    for column = 1:columns
%         if row == 2 || row == 3 && column == 3 || column == 4
         if (row == 2 || row == 3)
            if (column == 3 || column == 4)
                B = [B A(row)]
            end
        end
    end
end
B = 2
B = 1×2
     2     2
B = 1×3
     2     2     5
B = 1×4
     2     2     5     5
disp(B);
     2     2     5     5

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Shuoze Xu 2022-3-22

My expectation is to remove the elements in the third and fourth columns of the second row, and the third and fourth columns of the third row and print the array.

Shuoze Xu 2022-3-22