concatenate different matrices with different dimensions

Question

Jorge Luis Paredes Estacio 2023-6-29

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1989638-concatenate-different-matrices-with-different-dimensions

编辑： Shantanu Dixit 2023-7-1

Hello, I am obtaining 3 matrices with two colums each of then (the first column contains the time and the second column contains the acceleration) that represents the acceleration components of earthquake signals that can be represented as X, Y and Z matrices. So, these matrices may have the following size: X (520x2), Y(480x2) and Z(500x2) as an example. If I want to concatenate the matrices horizontally using this command:

data = horzcat(X,Y,Z), it will not work as they have different sizes.

The final size of the matrix (data) should be 520x6 (based on the highest length of colums of the three matrices X,Y and Z). So, zeros should be added at the end of each matrix with lower column size convert Y(480x2) and and Z(500x2) into Y(520x2) and Z(520x2) and then the three matrices be concatenated horizontally to create the matrix data(520x6). Thank you for your help.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Jorge Luis Paredes Estacio 2023-6-29

Thank you very much. It works perfectly :).

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Shantanu Dixit 2023-6-29

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1989638-concatenate-different-matrices-with-different-dimensions#answer_1264668

编辑：Shantanu Dixit 2023-7-1

在 MATLAB Online 中打开

Hi Jorge,

Yes you are right, horzcat requires the number of rows to be the same and for that padding needs to be done as you've explained in your question.

Max number of rows among the three matrices are 520 or can be found through as well

maxRows = max([size(X, 1), size(Y, 1), size(Z, 1)]);

Pad the matrices Y and Z with zeros at the end to match the maximum number of rows using the padarray() function, Since zeros need to be added at the end you need to use 'post' as the argument.

    Y = padarray(Y, [maxRows - size(Y, 1), 0], 'post');
    Z = padarray(Z, [maxRows - size(Z, 1), 0], 'post');

Number of rows are same now, use horzcat to concatenate the matrices horizontally.

Refer to the documentation:

horzcat - MATLAB

pad array - MATLAB

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Jorge Luis Paredes Estacio 2023-6-29

Thank you very much :). It is very usefull.

请先登录，再进行评论。

Answer 2

Sushma Swaraj 2023-6-29

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1989638-concatenate-different-matrices-with-different-dimensions#answer_1264698

在 MATLAB Online 中打开

Hi,

Assuming you have X,Y and Z matrices with different sizes:

% Determine the maximum no.of rows among X,Y and Z
maxRows = max([size(X, 1), size(Y, 1), size(Z, 1)]);
% Create zero matrices to match the no.of rows
Y_zeros = zeros(maxRows, size(Y, 2));
Z_zeros = zeros(maxRows, size(Z, 2));
% Assign the original data to the zero matrices
Y_zeros(1:size(Y, 1), :) = Y;
Z_zeros(1:size(Z, 1), :) = Z;
% Concatenate X,Y_zeros and Z_zeros horizontally
data = horzcat(X, Y_zeros, Z_zeros);