MATLAB Answers

Tom Wetherill

How do i remove rows from a column based on the value of a corresponding column?

Asked by Tom Wetherill
on 28 Mar 2013

I have a large amount of data that i need to process with Matlab but am quite a novice so unfamiliar with all but the basics. I effectively have a large data file containing thousands of entries and i need to know how i can remove a number of specific rows depending on the corresponding value if that makes any sense at all.

Column A is made up of depth values that range from .0000 to 2000.0000m and column B contains salinity values corresponding with each of these depths for a number of stations over a number of years. I want to find if i can remove all values from column B that correspond with values in column A that are less then or equal to 120.0000m.

If(A<=120.0000 then delete B)

I tried to convey this as best as i could in the expression above but don't know where to start with actual equations so any help would be much appreciated.

  1 Comment

per isakson
on 28 Mar 2013

The data is that the content of a file or the value of a variable?


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2 Answers

Answer by Wayne King
on 28 Mar 2013
Edited by Wayne King
on 28 Mar 2013
 Accepted answer

Assume X is your data matrix,

Xnew = X(X(:,1)>120,:);

So for example:

    X = randi(10,10,2);
    Xnew = X(X(:,1)>6,:);

I'm assuming that by column A you mean the 1st column of the matrix.


Answer by Mahdi
on 28 Mar 2013
Edited by Mahdi
on 28 Mar 2013

If you also want to remove these values from matrix A, then


  1 Comment

on 28 Mar 2013

The above assumes that you only have one column. If it's in the first column, use A(:,1) and B(Remove,1) and so on.

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