Store vector data of not fixed length into a Matrix

Question

Maximilian Arpaio 2018-9-17

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/419363-store-vector-data-of-not-fixed-length-into-a-matrix

编辑： Maximilian Arpaio 2018-9-17

Dear community, I am trying to store different vectors 1 x N inside a Matrix M x N. The issue in doing this is that the vectors have not the same length N (which is variable for each row) and thus each row M does not have the same number of columns N. I've tried to allocate a zero matrix in advance so that deltas could have been filled in by zeros, but it is not working. How can I overcome this ?

example: A=zeros (8) A(3)=[1 2 3 4] A(1)=[2 6 7 9] A(2)=[4 6 6 7 8 9 1 3]

A(3) and A(1) assignments are returning me an error while A(2) assignment not. For those arrays < 8 elements, I was hoping to get 0s as fill ups to comply to the matrix's length.

Please advise...

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

John D'Errico 2018-9-17

No need to post twice.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

John D'Errico 2018-9-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/419363-store-vector-data-of-not-fixed-length-into-a-matrix#answer_337149

编辑：John D'Errico 2018-9-17

在 MATLAB Online 中打开

You cannot store entire vectors into a double matrix as you tried to do. So this is impossible:

A(1)=[2 6 7 9]
A(2)=[4 6 6 7 8 9 1 3]

First, a flat (double precision) array cannot store multiple elements into a single element of that array. Second, an array cannot have rows (or columns) of different lengths.

You must either use a cell or struct array, or store the vectors properly inside a double array. So you COULD have done this:

A(1,1:4)=[2 6 7 9]

but then you are forced to know how long the vector is in advance.

A cell array is fully a better choice.