rows extraction in matrix depending on a column value

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PK 2013-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/80553-rows-extraction-in-matrix-depending-on-a-column-value

评论： Saumy Tewari 2021-1-27

I have a 50x50 matrix and n that the last row has 0,1,2 at different locations ie., 0 n 10 rows,1 n 20 rows ad 2 in 20 rows, so depending on the column value how can i extract all rows containing 0 at 50th column and save them in to a single variable

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Sean de Wolski 2013-6-28

A small example of your matrix and expected results would make this much easier to grasp.

PK 2013-6-28

编辑：PK 2013-6-28

@Sean de Wolski A=[1 2 3 0; 1 2 5 0;5 8 6 1;6 8 7 0;5 4 7 2;6 5 8 0] so in this there are 6 rows and depending on fourth element of the row all the rows containing same number are to be pinned up to a single variable ie.,rows 1,2,4,6 are to be stored to a single variable and row 3 to another and row 5 to another.

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Answer 1

Image Analyst 2013-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/80553-rows-extraction-in-matrix-depending-on-a-column-value#answer_90249

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Try this:

% Generate sample data
A=[...
1 2 3 0; 
1 2 5 0;
5 8 6 1;
6 8 7 0;
5 4 7 2;
6 5 8 0]
% Get last column
lastColumn = A(:, end);
% Get zeros
A0 = A(lastColumn == 0, :)
% Get zeros
A1 = A(lastColumn == 1, :)
% Get zeros
A2 = A(lastColumn == 2, :)

In the command window:

A =
   2     3     0
   2     5     0
   8     6     1
   8     7     0
   4     7     2
   5     8     0
A0 =
   2     3     0
   2     5     0
   8     7     0
   5     8     0
A1 =
   8     6     1
A2 =
   4     7     2