MATLAB: Exclusion of Columns in a matrix

columns matrixmatrix manipulation

My question is: I want to delete columns that possess the sum equal 1, however, when I use the function "for" occurs a problem….For each time that is deleted a column, the matrix is decreasing the number of columns, so that index used above exceed size of matrix….how can I solve this problem?
 for j=1:794;
    if S(j,1)==1;
        X(:,j)=[];
    end
end
when perform this command is showed:
 ???  Index of element to remove exceeds matrix dimensions.
thanks

Best Answer

X = X(:,~abs(sum(X) - 1)<1e3*eps);
OR
S = sum(X);
X = X(:,~abs(S - 1)<1e3*eps);
OR
X = X(:,abs(sum(X) - 1)>1e3*eps);
e.g.
>> X = randi(23,5)
X =
     7    12    18    23    20
    16    23     6    13     6
    16     8    12     4    19
     4    14    17     4     6
     3     6    21     6    22
>> X(:,3) = .2
X =
            7           12          0.2           23           20
           16           23          0.2           13            6
           16            8          0.2            4           19
            4           14          0.2            4            6
            3            6          0.2            6           22
>> X = X(:,abs(sum(X) - 1)>1e3*eps)
X =
     7    12    23    20
    16    23    13     6
    16     8     4    19
     4    14     4     6
     3     6     6    22
>>
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