MATLAB: Replace Nan in array with the previous value/text/number

cell arraysdata

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 cellfun(@isnan,A(i,j))
        A(i,j) = I
    else
        I  = A(i,j)
    end
   end
end
I use this function 
data={'Robert',NaN,5,6,7,8,NaN,NaN,NaN};
fill_nans(data)  %working ok
data2={'Robert','pai',NaN,5,6,7,8,NaN,NaN,NaN};
fill_nans(data2) %Not working error is

data3={'Robert',NaN,NaN,5,6,7,8,'pai',NaN,NaN,NaN};
fill_nans(data2) %Not working error is
Error using cellfun
Non-scalar in Uniform output, at index 1, output 1.
Set 'UniformOutput' to false.
Error in fill_nans (line 8)
if cellfun(@isnan,A(i,j))

Best Answer

Explanation: you forgot to consider what isnan returns with a non-scalar input (such as when you provide it with those character vectors) (hint: it returns a non-scalar logical array of the same size as the input array)
Solution: simply define an anonymous funciton that only return TRUE for numeric scalars (as well as being NaN) (i.e. the output of this function is always scalar):
fun = @(a) isnumeric(a)&&isscalar(a)&&isnan(a);
...
if cellfun(fun,A(i,j))
    ...
end
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