How do I remove all the rows with NaN-value of a specific column?

Hey, I want to delete all the rows with NaN value of my first column using the 'isnan'-function. The matrix is 570x9.

After I do that I need to delete all columns of the matrix with >25% NaNs, also using the 'isnan'-function.

Thanks in advance for the answers! I'm sure the solution is really basic but I can't get my head around it.

Answer 1

[dpb]

X(isnan(X(:,1)),:)=[];          % solution a -- remove those rows w/ NaN in column 1
X=X(~isnan(X(:,1)),:);          % solution b -- keep only those rows NOT NaN in column 1
X=X(isfinite(X(:,1)),:);        % solution c -- keep only those rows NOT NaN|Inf in column 1

NB: Solution C is a different result than either A or B IFF (if and only if) column one also might contain Inf values besides NaN.

X=X(~isnan(X(:,1)),:);
isGood=sum(isnan(X))<=(size(X,1)/4);
X=X(:,isGood);

[Niklas Weichbold]

Thank you very much! I'm new to Matlab and haven't figuered out all the different coding options yet

[dpb]

Read the documentation section on logical indexing -- most powerful.