Exclusion of Columns in a matrix

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Alan
Alan 2012-1-3
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

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Andrei Bobrov
Andrei Bobrov 2012-1-3
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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Andrei Bobrov
Andrei Bobrov 2012-1-3
in this is case not need use loops "for..end".
just use e.g.:
X = X(:,abs(sum(X) - 1)>1e3*eps);

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