How to select specific row in a matrix

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Ikra89
Ikra89 2013-2-11
Hi all..
i have a problem to select every row.
for eg:
i have matrix 100x13.
i want to select data which position in row 1-5, 21-25, 41-45, 61-65, 81-85.
so i have 2 new matrixs. first as i described above, and the second is the rest (6-20, 26-40, 46-60, 66-80, 86-100).
i want to apply k-fold method to get training data and testing data.
thanks a lot if somebody can help me.
regards
Ikra

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回答（2 个）

Shashank Prasanna
Shashank Prasanna 2013-2-11
A = rand(100,4);
ind_logical = logical(ones(100,1));
ind_logical([1:5, 21:25, 41:45, 61:65, 81:85])=false;
B = A(~ind_logical,:);
C = A(ind_logical,:);
  2 个评论
Jan
Jan 2013-2-11
true(100, 1) is more efficient than creating a double array at first and convert it ino a logical. But the logical indexing is an efficient method here in general: +1.
Ikra89
Ikra89 2013-2-13
编辑：Ikra89 2013-2-13
i try to change A = rand(100,4) to fix dimension become 75x13 and 25x13, but the output is different from the real data.
in this case i just want to select data, not to change. thanks a lot for your answer, but if you can fix it, i really appreciate your help.

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Thorsten
Thorsten 2013-2-11
编辑：Thorsten 2013-2-11
X = rand(100, 13);
ind0 = 1:5; ind1 = ind0;
for i = 1:4, ind1 = [ind1 ind0 + 20*i]; end
ind2 = setdiff(1:100, ind1);
A = X(ind1, :);
B = X(ind2, :);
  1 个评论
Ikra89
Ikra89 2013-2-13
编辑：Ikra89 2013-2-13
wrong answer. your program not too different with benji bowbow in above. why the output is different with the data? in this case i just want to select data, not to change. thanks a lot for your answer, but if you can fix it, i really appreciate your help.

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