Remove NaN from a matrix

Hi,

I have matrix B = (366 x 39) and has NaN values in every column. How can I remove NaN and obtain the mean of every column. The resulting matrix C should be a 1 x 39 matrix.

Thanks in advance.

Answer 1

[George Papazafeiropoulos]

ind=sum(~isnan(B));
B(isnan(B))=0;
mean=sum(B)./ind

Answer 2

[James Tursa]

If you have the appropriate toolbox, you can use the function: nanmean

[Damith]

Thanks

Answer 3

[dpb]

If have the Stats Toolbox, then just nanmean

If don't, it's more of a pain; unless the NaN are consistent in number per column you'll end up w/ a "jagged" array which isn't allowed in an array. Hence you'll need to accumulate by column--the "deadahead" solution is a loop and for small matrices of this order it'll undoubtedly be "fast enough"...

nc=size(B,2);   % number columns in B
m=zeros(1,nc);  % preallocate for the means vector
for i=1:nc
  m(i)=mean(isfinite(B(:,i)));  % compute mean of values less NaN's and Inf's
end

You can use accumarray for this w/o the loop...seed doc's for details

[Damith]

Thanks.

Answer 4

[Image Analyst]

You might want to take a look at John D'Errico's inpaint_nans: http://www.mathworks.com/matlabcentral/fileexchange/4551-inpaint-nans