Creating matric of multiple arrays

Question

Nicholas Moung 2021-1-20

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/722435-creating-matric-of-multiple-arrays

评论： Adam Danz 2021-1-20

采纳的回答： Bob Thompson

x=0:12;

k=5;

a=k+x;

b=k+2x;

c=k+4x;

d=kx;

I'd like to create 2*2 matrix of four arrays (a,b,c,d).

Z=[a b; c d];

How could I realize this task by using for loop? Or do you have any other way to realize it? I ask for your advice! Thank you in advance!

2 个评论
显示无隐藏无

Bob Thompson 2021-1-20

What are you looking to loop? Your setup looks fine for a single iteration, so 'looping' should just be a matter of identifying what you want to change, and putting it, and the affected equations, inside a loop.

Nicholas Moung 2021-1-20

This is just an example. The real formulae need the iteration. For instant, a,b,c and d are 1*100 arrays (when x=1:100;), and the matrix Z will be the 2*2 matrix formed by those a,b,c and d and each of the element of this matrix Z must be 1*100 array. And the formulae for a,b,c and d are just examples. Thank you for discussing!

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Bob Thompson 2021-1-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/722435-creating-matric-of-multiple-arrays#answer_602515

在 MATLAB Online 中打开

You should be able to accomplish what you're looking for with some matrix indexing, no loop necessary.

x = 1:100;
k = 12;
a = x + k; % Makes a 100x1 size array, 13:112
b = 2*x + k; % Makes a 100x1 size array following the same formula
c = 4*x + k;
d = x * k;
% Adding a third dimension of Z allows you to basically stack each of the elements of a, b, c, and d
% into the one 2x2 format. Z(:,:,1) is a 2x2 of [a(1), b(1); c(1), d(1)], and each subsequent 'sheet'
% takes you to the next set of elements in the four matrices.
Z(1,1,:) = a;
Z(1,2,:) = b;
Z(2,1,:) = c;
Z(2,2,:) = d;

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Nicholas Moung 2021-1-20

Thank you so much! It does work!

请先登录，再进行评论。

Answer 2

Adam Danz 2021-1-20

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/722435-creating-matric-of-multiple-arrays#answer_602527

编辑：Adam Danz 2021-1-20

在 MATLAB Online 中打开

Perhaps this (scroll down to see vectorized version)?

x=0:12;
k=5;
a=k+x;
b=k+2*x;
c=k+4*x;
d=k*x;
Z = nan(2,2,numel(x));
for i = 1:numel(x)
    Z(:,:,i) = [a(i) b(i); c(i) d(i)];
end
disp(Z)
(:,:,1) =

     5     5
     5     0

(:,:,2) =

     6     7
     9     5

(:,:,3) =

     7     9
    13    10

(:,:,4) =

     8    11
    17    15

(:,:,5) =

     9    13
    21    20

(:,:,6) =

    10    15
    25    25

(:,:,7) =

    11    17
    29    30

(:,:,8) =

    12    19
    33    35

(:,:,9) =

    13    21
    37    40

(:,:,10) =

    14    23
    41    45

(:,:,11) =

    15    25
    45    50

(:,:,12) =

    16    27
    49    55

(:,:,13) =

    17    29
    53    60

If so, you don't need a loop.

Z = reshape([a;c;b;d],2,2,numel(x))  % Assuming a,b,c,d are row vectors
Z = 
Z(:,:,1) =

     5     5
     5     0

Z(:,:,2) =

     6     7
     9     5

Z(:,:,3) =

     7     9
    13    10

Z(:,:,4) =

     8    11
    17    15

Z(:,:,5) =

     9    13
    21    20

Z(:,:,6) =

    10    15
    25    25

Z(:,:,7) =

    11    17
    29    30

Z(:,:,8) =

    12    19
    33    35

Z(:,:,9) =

    13    21
    37    40

Z(:,:,10) =

    14    23
    41    45

Z(:,:,11) =

    15    25
    45    50

Z(:,:,12) =

    16    27
    49    55

Z(:,:,13) =

    17    29
    53    60