how to remove rows if only the first row contains a specified value

Hey everyone,

How can I easily remove an entire row if only the first element of a row contains a certain value (thus only checking the first column).

I would like to use a function that only checks the first column for a value (e.g. 281) and if that value is found then subsequently deletes that row. in the example below that would result in D = [279;280, 6;7, 6;5]

[EDIT]: how can I include more than value? Is this possible with & or | ?

example:

A = [279; 280; 281];
B = [6; 7; 9];
C = [6; 5; 4];

D = [A B C];

Answer 1

[Stephen23]

One Value: the simple MATLAB way, either keeping the other rows:

>> X = D(:,1)~=281;
>> D = D(X,:)
D =
   279     6     6
   280     7     5

Or by removing those rows:

>> X = D(:,1)==281;
>> D(X,:) = []
D =
   279     6     6
   280     7     5 

Multiple Values: use ismember, either keeping the other rows:

>> V = [281,279]; % values to be removed.
>> X = ismember(D(:,1),V);
>> D = D(~X,:)
D =
   280     7     5

Or by removing those rows:

>> X = ismember(D(:,1),V);
>> D(X,:) = []
D =
   280     7     5

[Felix Flores James]

This worked!! Thank you so much for your help