replace nan in a matrix with specific values

I do not know why the following code does not work

I have a matrix F which has some of nan entries, and i have saved the last row of this matrix as N_lastrow. then I want to replace all nan entries in this row such that if F is 4*4 matrix and if N_lastrow(4,4)= nan , then replace it directly by the mean of the whole rest of entries in F. However, any other nan values such that if N_lastrow(1,2)=nan, we have to replace it by the value of of F(3,3) and if it is also nan I will replace it by F(2,4), and if it is also nan then replace it by the mean of the whole rest of entries.

THIS IS THE CODE

f;

N_lastrow=f(n,:);% where n is the number of rows in f

for k=1:n

if isnan(N_lastrow(1,k))

if k==n

N_lastrow(1,k)=nanmean(f,'all')

break

end

for m=n:1

if m-1 >0

N_lastrow(1,k)=f(m-1,k+1)

if ~isnan(f(m-1,k+1))

break

end

else

N_lastrow(1,k)=nanmean(f,'all')

end

end

else

N_lastrow(1,k)=f(n,k)

end

end

N_lastrow

Answer 1

[Kevin Holly]

Can you give clarity to what you want? To me, it sounds like you want something like this:

f = [1 2 3 2; 4 5 6 1; 7 8 9 2];
f(4,4) = NaN

f = 4×4

1 2 3 2 4 5 6 1 7 8 9 2 0 0 0 NaN

N_lastrow=f(end,:)

N_lastrow = 1×4

0 0 0 NaN

if isnan(f(4,4))
    f(4,4) = f(3,3);
    if isnan(f(3,3))
        f(4,4) = f(2,4);
        if isnan(f(4,4))
            f(4,4) = mean(f,'omitnan');
        end
    end
end
f

f = 4×4

1 2 3 2 4 5 6 1 7 8 9 2 0 0 0 9

N_lastrow=f(end,:)

N_lastrow = 1×4

0 0 0 9

[Hajar Alshaikh]

no. if N_lastrow(1,n) is nan then direct f(n,n) = mean(f,'omitnan');

so f(4,4)=f(3,3) is not right

please review the code that I wrote up

my question is why nan still appear after i run my code?