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How to delete all rows of an array that have a specified number in a particular column?

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How can you delete a row of an array if the number in a particular column doesn't equal a specified number or even multiple numbers? For example, let A = magic(5). How can we delete any row where A(2,:) = 5? B=A(A(:,2)~=5) doesn't quite do it, only gives me the first column. In this case, there's only one row, but I'm looking for a general solution.

Accepted Answer

Walter Roberson
Walter Roberson on 30 Mar 2022
A(:, A(2,:) == 5) = [];
  2 Comments
L'O.G.
L'O.G. on 30 Mar 2022
Edited: L'O.G. on 30 Mar 2022
@Walter Roberson Thanks, but that removes the column with that value, not the row. I realized (thanks to you!) that this is what I want: A(A(2,:) == 5,:) = [];
Walter Roberson
Walter Roberson on 30 Mar 2022
How can we delete any row where A(2,:) = 5
A(2,:) is a query about contents of row 2, not about a particular column. It does not make sense to ask about removing rows for which something is true about row 2.
If you want to deal with columns, then
A = magic(5)
A = 5×5
17 24 1 8 15 23 5 7 14 16 4 6 13 20 22 10 12 19 21 3 11 18 25 2 9
A(A(:,2) == 5, :) = []
A = 4×5
17 24 1 8 15 4 6 13 20 22 10 12 19 21 3 11 18 25 2 9

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