MATLAB: Replace NaN with next good value in a certain column of a table

cellnantable

I have T2.mat which is a table with 12 columns. I want to replace NaN in columns 5:7 (5 to 7) by exactly the next good value in each column. I don't want to replace NaN in other columns.

I searched a lot and tried hard to do this. I was read the question in the link below:

https://www.mathworks.com/matlabcentral/answers/337273-how-can-i-replace-nan-elements-with-the-nearest-value-in-the-same-column

but I want to do this in just columns 5 to 7 and not for rest of the columns. I attached T2.mat if it's help

Does anyone know how I can do this?

Thank you,

Behzad

Best Answer

It's as simple as:

T2 = fillmissing(T2, 'next', 'DataVariables', {'lat', 'lon', 'station_elevation'})

T2 = fillmissing(T2, 'next', 'DataVariables', 5:7)

I recommend the first expression as it is clearer as to which variable is to be filled (and will work even if the order of the columns changes).

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I can't run your code but here are some feedback at first glance.

First, always use correct indentation so that it's much easier to read the code. "Smart indentation" can be done by selecting all of the code and pressing ctrl+i.

See my 3 notes within your code.

% allDates should be out of the loop because it's not necessary to be in the loop
dt1 = datetime([1982 01 01]);
dt2 = datetime([2018 12 31]);
allDates = (dt1 : calmonths(1) : dt2).';
allDates.Format = 'MM/dd/yyyy';
% 1) pre-allocate a cell array that will store 
%   your tables (see note #3)
T2 = cell(size(x);  % this should work, I don't know what x is
% creating loop
for idx = 1:numel(x)
    T = readtable(idx);
    % 2) This line should probably be T = readtable(x(idx));
    
        
    sort = sortrows(T, 8);
    selected_table = sort (:, 8:9);
    tempTable = table(allDates(~ismember(allDates,selected_table.data)), NaN(sum(~ismember(allDates,selected_table.data)),size(selected_table,2)-1),'VariableNames',selected_table.Properties.VariableNames);
    T2 = outerjoin(sort,tempTable,'MergeKeys', 1);
    T2 = fillmissing(T2, 'next', 'DataVariables', {'lat', 'lon', 'station_elevation'})
    % 3) You're overwriting the variabe T2 on each iteration of the i-loop. 
    % to save each table, do this
    % T2{idx} = fillissing(.....)
end

Now, to access table #n, T2{n}

As I said, I can't run your code so if you come across problems, show me the updated code and describe what went wrong.

Also, it would be a very wise investment of your time to spend 1/2 an hour teaching yourself how to debug code using debug mode.

MATLAB: Replacing elements in a table

A=table2array(A);
A(isinf(A)|-isinf(A))=nan;
A=array2table(A)

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