How to delete columns of a matrix that have fewer than 3 non-zero elements

Hello,

How can I delete columns of a matrix that have fewer than 3 non-zero elements? Thank you!

[osminbas]

This is assuming matrix is nxn and n>>3.

[Sean de Wolski]

Like fewer than three non-zero elements or is it a cell array ? Please define:

A = magic(5); %all columns have 5 elements

[osminbas]

Yes, that is what I meant. Fewer than 3 non-zero elements.

[osminbas]

I can define it as matrix A is 5x5. Say two columns (column 1 and 3) have only 2 non-zero elements.

Answer 1

[Wayne King]

Hi, I'm sure this isn't the most efficient way:

x =[
     5     0     1     4     1
     3     0     0     2     1
     1     0     2     2     4
     4     3     0     2     3
     4     2     0    1     3];

for nn =1:size(x,2) 
     numz(nn) = length(find(x(:,nn)==0)); 
 end
 x(:,numz>2) = [];

[osminbas]

Actually I did this:

for nn =1:size(x,2)

numz(nn)=length(find(x(:,nn)~=0));

end

x(:,numz<3)=[];

It worked! Thank you!