# how convert the vector to matrix ? unknown number of columns

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reta jon 2021년 7월 29일
댓글: Image Analyst 2021년 7월 31일
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]
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Matt J 2021년 7월 31일
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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### 답변(2개)

dpb 2021년 7월 29일
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
>>
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Image Analyst 2021년 7월 31일
@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 2021년 7월 29일
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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