CODEWITHSUNDEEP
matlabnan
Omer
Omer

Reputation: 115

How to logically replace a NaN value with previous non-NaN value in Matlab?

I have a matrix data, that I am saving into data_Buffer. All values <=-999 in data are replaced by NaN and stored in data_Buffer. This is my code:

fid = fopen('D:\Data\');
data = fread(fid,'*int16');% 21 x 200 matrix
fclose(fid);

data(data <= -999) = nan;
s = size(data,2);
data_Buffer(:,k:k+s-1) = data;% This is a buffer to store the data matrix

Questions/requirements:

1) In data_Buffer, how can I see search for NaN values in a row and replace them with the previous non-NaN value? The algorithm should start from the first column and move towards the last column (i.e., if there is a NaN in column 10, it should be replaced by the valid value from column 9).

2) If there are several consecutive NaN values, they should be replaced by the previous non-NaN value in the row.

Upvotes: 1

Views: 834

Answers (1)

Omer
Omer

Reputation: 115

I solved it using the solution provided by Matt at Matlab Central and modified it for case of rows instead of columns:

function A = fill_nans(A)
% Replaces the NaN in each column with 
% previous non-NaN values.

for i = 1:size(A,1)
   I = A(1,i);
   for j = 2:size(A,2)
    if isnan(A(i,j))
        A(i,j) = I;
    else
        I  = A(i,j);
    end
end

Upvotes: 1

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