how convert the vector to matrix ? unknown number of columns

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reta jon
reta jon on 29 Jul 2021
Commented: Image Analyst on 31 Jul 2021
Is it possible to convert the vector to matrix .unknown number of columns and the number of row is known. Where is the row filled with zeros? Or with holes?
A=[1 2 3 4 5 6 7 8 9]
number of row=3
A=[1 2 3 4
5 6 7 8
9 0 0 0]
  1 Comment
Matt J
Matt J on 31 Jul 2021
The task is ambiguous without additional specifications on how the number of columns is to be chosen. For example, with the input,
A=[1 2 3 4 5 6 7 8 9 10 11 12 13 14 15];
nrows=3;
there are at least three possible 3-row arrangements that would be valid:
B=[1 2 3 4 5
6 7 8 9 10
11 12 13 14 15]
B=[1 2 3 4 5 6
7 8 9 10 11 12
13 14 15 0 0 0]
B=[1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 0 0 0 0 0 0]

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Answers (2)

dpb
dpb on 29 Jul 2021
A=1:9;
nRow-3;
>> A=reshape(A,3,[])
A =
1 4 7
2 5 8
3 6 9
>>
The posted in the Q? text above forced four columns, not three (3) rows...
That, of course, is also doable with a little more effort...
A=1:9;
nCol=4;
nZ=ceil(numel(A)/4);
>> reshape([A zeros(1,nCol*nZ-numel(A))],nCol,[]).'
ans =
1 2 3 4
5 6 7 8
9 0 0 0
>>
  6 Comments
Image Analyst
Image Analyst on 31 Jul 2021
@Matt J, yes there are multiple possible answers. But since he did not actually ask how to construct any of them, and all he asked was "Is it possible to convert the vector to matrix .unknown number of columns and the number of row is known?" the answer is simply "Yes".

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Matt J
Matt J on 29 Jul 2021
No, the solution is ill-defined. Another result with the same number of rows is:
A=[1 2 3
4 5 6
7 8 9]

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