how to split an 8x8 2D array

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Freja 2023-8-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2007097-how-to-split-an-8x8-2d-array

评论： C B 2023-8-10

how would I split an 8x8 2D array into four 4x4 arrays so that I can take the mean of each 4x4 array using the mean function?

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Answer 1

C B 2023-8-10

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2007097-how-to-split-an-8x8-2d-array#answer_1285892

编辑：C B 2023-8-10

在 MATLAB Online 中打开

Is this what you are looking for?

% Sample 8x8 array
A = reshape(1:64, [8,8])
A = 8×8
     1     9    17    25    33    41    49    57
     2    10    18    26    34    42    50    58
     3    11    19    27    35    43    51    59
     4    12    20    28    36    44    52    60
     5    13    21    29    37    45    53    61
     6    14    22    30    38    46    54    62
     7    15    23    31    39    47    55    63
     8    16    24    32    40    48    56    64
% Splitting into 4x4 arrays
A1 = A(1:4, 1:4)
A1 = 4×4
     1     9    17    25
     2    10    18    26
     3    11    19    27
     4    12    20    28
A2 = A(1:4, 5:8)
A2 = 4×4
    33    41    49    57
    34    42    50    58
    35    43    51    59
    36    44    52    60
A3 = A(5:8, 1:4)
A3 = 4×4
     5    13    21    29
     6    14    22    30
     7    15    23    31
     8    16    24    32
A4 = A(5:8, 5:8)
A4 = 4×4
    37    45    53    61
    38    46    54    62
    39    47    55    63
    40    48    56    64
% Computing the mean for each 4x4 array
mean_A1 = mean(A1(:));
mean_A2 = mean(A2(:));
mean_A3 = mean(A3(:));
mean_A4 = mean(A4(:));
% Displaying the results
fprintf('Mean of A1: %f\n', mean_A1);
Mean of A1: 14.500000
fprintf('Mean of A2: %f\n', mean_A2);
Mean of A2: 46.500000
fprintf('Mean of A3: %f\n', mean_A3);
Mean of A3: 18.500000
fprintf('Mean of A4: %f\n', mean_A4);
Mean of A4: 50.500000

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Freja 2023-8-10

yes thank you! also would there be a way to create a loop to index that and do each calculation for you?

C B 2023-8-10

在 MATLAB Online 中打开

Yes we can use loop for splitting and Mean calculation

A = reshape(1:64, [8,8]);
mean_values = zeros(1, 4);
% Loop to extract 4x4 matrices and compute mean
for row = 1:2
    for col = 1:2
        r = (row-1)*4 + 1 : row*4;
        c = (col-1)*4 + 1 : col*4;
        
        submatrix = A(r, c);
        idx = (row-1)*2 + col;
        mean_values(idx) = mean(submatrix(:));
    end
end
for i = 1:4
    fprintf('Mean of A%d: %f\n', i, mean_values(i));
end
Mean of A1: 14.500000
Mean of A2: 46.500000
Mean of A3: 18.500000
Mean of A4: 50.500000