Fill NaNs in array with last value

Hi all, thanks for your help. I have a double array and I want to fill NaN values with the last value.

Example:

[321 nan() nan() nan() nan() 55 nan() nan() nan() 22 nan() 21 nan() nan()]

desired result

[321 321 321 321 321 55 55 55 55 22 22 21 21 21]

Also I want to do this same thing with a cell array of strings with blanks instead of NaN. I'm trying to avoid ugly for loops here. This seems familiar... maybe it was a cody question I couldn't solve. Thanks again.

Answer 1

[Sean de Wolski]

You still have to figure out what to do if the first value is nan.

v = [321 nan() nan() nan() nan() 55 nan() nan() nan() 22 nan() 21 nan() nan()];
idx = (~isnan(v)); %non nans
vr = v(idx); %v non nan
v2 = vr(cumsum(idx)) %use cumsum to build index into vr

[Sean de Wolski]

Oh, and for cell-arrays use cellfun(@isempty... intead of isnan to build idx.

[Image Analyst]

Clever!

[Leah]

ya wow... impressive. thank you!

Answer 2

[Jan]

What's wrong with FOR loops?

data = [321 nan() nan() nan() nan() 55 nan() nan() nan() 22 nan() 21 nan() nan()];
for k = find(isnan(data))
  data(k) = data(k - 1);
end

But here a vectorized version:

notNaN = ~isnan(data);
index  = find(notNaN);
fillup = zeros(size(data));
fillup(notNaN) = index - [0, diff(index)];
result = data(cumsum(fillup));

Much uglier than the loop. I cannot test this currently. You have to care for initial NaNs in addition. And Sean's solution is nicer.

[Khaing Zin Htwe]

if true
  % data = [321 nan() nan() nan() nan() 55 ;nan() nan() nan() 22 nan() 21; nan() nan() 3 66 5 8];
end

I want to fill with integer zeros to NaN values,sir. How can I do it? please help me.

[Shruti Verma]

This should do it :)

data(isnan(data)) = 0;