How can I replace NaN elements with the nearest value in the same column?

I am trying to replace NaN's in a vector field with the nearest value.

 % I have:
M=
NaN  12
18   14
NaN  NaN
NaN  NaN
NaN  16
12   NaN
12   NaN
NaN  12
16   NaN

 %I desire:
M=
18   12
18   14
12   16
12   16
12   16
12   12
12   12
16   12
16   12

Any information will be helpful. Thank you

[AstroGuy1984]

What do you mean by "nearest"? Do you mean "next good value"? Because that's what you appear to desire. For example the second NaN in column 1 is closer to 18 than 12.

[sal135]

I would like to have the first value of NaN to have the value of the next good value. However if the last value in the column is a NaN I would like for it to have the value of the previous good value

Answer 1

[Andrei Bobrov]

FIXED 2

m = flipud(M)
t = ~isnan(m);
ii = cumsum(t);
ii(ii == 0) = 1;
ii = bsxfun(@plus,[0,ii(end,1:end-1)],ii);
m1 = m(t);
out = flipud(m1(ii))

[sal135]

I keep getting an error of: Undefined function 'flip' for input arguments of type 'double'.

[Andrei Bobrov]

You are using an older version of MATLAB. Fixed for you.

[sal135]

Yeah I just realized that. However now I get Error using + Matrix dimensions must agree.

[Andrei Bobrov]

Op! Clear. Fixed.

[Andrei Bobrov]

>> m = flipud(M);
t = ~isnan(m);
ii = cumsum(t);
ii(ii == 0) = 1;
ii = bsxfun(@plus,[0,ii(end,1:end-1)],ii);
m1 = m(t);
out = flipud(m1(ii))
out =
    18    12
    18    14
    12    16
    12    16
    12    16
    12    12
    12    12
    16    12
    16    12
>>

[sal135]

Thank you for your help! This worked out great.

Answer 2

[dpb]

Check out <Fileexchange/4551-inpaint-nans>