For loop to create a matrix array

Question

0 个投票

I have a data X say

X= 1:100 (integer 1 to 100)

I want to write a for loop that will create matrix of w=10x5 (10rows, 5 columns) where by column 1 will be the first 10 elements of X (1 to 10), column 2 (11 to 20) and so on and then stop at column 5 (41 to 50) before creating another matrix say w2 (ie starting the iteration again).

I don't want to use reshape function as it won't fit into the real data I am working on.

4 个评论
显示 2更早的评论隐藏 2更早的评论

Image Analyst 2022-2-6

编辑：Image Analyst 2022-2-6

For 90, what are the sizes of the two matrices?

9-by-5? (in which case, my answer below works)
Or one matrix of 10-by-5 and the second one of 10-by-4?

Cutie 2022-2-7

I appreciate @Matt J and @Image Analyst for offering your help.

请先登录，再进行评论。

请先登录，再回答此问题。

Follow Question

Answer 1

Matt J 2022-2-6

编辑：Matt J 2022-2-6

在 MATLAB Online 中打开

1 个投票

Because, I may need to create matrix of size 9 by 5. In which case I will only have 2 matrices formed from the first 90 elements (1:90) and the last 10 element can be discarded.

That doesn't disqualify reshape.

rows=9;
cols=5;
X=1:100;
M=rows*cols;
N=numel(X);
X=reshape( X(1:floor(N/M)*M)   ,rows,cols,[]);
w=squeeze(num2cell(X,[1,2]))
w = 2×1 cell array
    {9×5 double}
    {9×5 double}

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Cutie 2022-2-7

Thank you very much @Matt J. This works and it opens my eyes to other things.

请先登录，再进行评论。

Answer 2

Image Analyst 2022-2-6

编辑：Image Analyst 2022-2-6

在 MATLAB Online 中打开

0 个投票

Try this

N = 100; % or 90 or some other multiple of 10
X= 1 : N; % (integer 1 to 100)
x1 = reshape(X(1:N/2)', N/10, [])
x1 = 10×5
  11    21    31    41
  12    22    32    42
  13    23    33    43
  14    24    34    44
  15    25    35    45
  16    26    36    46
  17    27    37    47
  18    28    38    48
  19    29    39    49
  20    30    40    50
x2 = reshape(X(N/2+1:end), N/10, [])
x2 = 10×5
  61    71    81    91
  62    72    82    92
  63    73    83    93
  64    74    84    94
  65    75    85    95
  66    76    86    96
  67    77    87    97
  68    78    88    98
  69    79    89    99
  70    80    90   100

If you don't want to use reshape for some weird reason, you can do it with a for loop but it will be more complicated.

X = 1 : 100;
x3 = zeros(10, 5);
x4 = zeros(10, 5);
k = 1;
for col = 1 : 5
    for row = 1 : 10
        x3(row, col) = X(k);
        x4(row, col) = X(k + 50);
        k = k + 1;
    end
end
x3
x3 = 10×5
     1    11    21    31    41
     2    12    22    32    42
     3    13    23    33    43
     4    14    24    34    44
     5    15    25    35    45
     6    16    26    36    46
     7    17    27    37    47
     8    18    28    38    48
     9    19    29    39    49
    10    20    30    40    50
x4
x4 = 10×5
    51    61    71    81    91
    52    62    72    82    92
    53    63    73    83    93
    54    64    74    84    94
    55    65    75    85    95
    56    66    76    86    96
    57    67    77    87    97
    58    68    78    88    98
    59    69    79    89    99
    60    70    80    90   100

3 个评论
显示 1更早的评论隐藏 1更早的评论

Navita 2023-2-21

Output not showing

Image Analyst 2023-2-21

@Navita as you can see above there is an output. I ran it in the editor with the green run triangle and there is definitely an output. Just look at my Answer and you can see it.

If you don't have any output then you must have copied my code and changed it somehow.

If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

请先登录，再进行评论。

For loop to create a matrix array

4 个评论
显示 2更早的评论隐藏 2更早的评论

采纳的回答

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

更多回答（1 个）

3 个评论
显示 1更早的评论隐藏 1更早的评论

类别

产品

版本

标签

Community Treasure Hunt

For loop to create a matrix array

4 个评论 显示 2更早的评论 隐藏 2更早的评论

采纳的回答

1 个评论 显示 -1更早的评论 隐藏 -1更早的评论

更多回答（1 个）

3 个评论 显示 1更早的评论 隐藏 1更早的评论

类别

产品

版本

标签

另请参阅

Community Treasure Hunt

4 个评论
显示 2更早的评论隐藏 2更早的评论

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

3 个评论
显示 1更早的评论隐藏 1更早的评论