How to select the last 6 values in a column?

Hi everyone.

I have a doubt. I need to do some horizontal interpolation and, to do it, i must replace NaN's with 0's (zeros).

I already have done the interpolation with the NaN's in the beginning of the data serie, but my problem starts within the last 6 values.

Here's an example:

To replace the NaN's that appears in the first 6 rows, i made this script:

for c=1:4
    x=isnan(DD(1:6,c));
    DD(x,c)= 0;
end

And everything went well.

Now, I must replace any NaN that appears in the last 6 rows of all columns. I tried to create a code for it, but it's not working

here it goes:

[row,col,page]=size(DD);
for c=1:4
    y=isnan(DD(row-5:row,c));
    DD(y,c)=0;
end

Anyone can help me, please?

It's very meaningful to me.

Answer 1

[Image Analyst]

Why not simply do:

DD(isnan(DD)) = 0;

Or if you really need to replace only nans in the last 6 rows only, and leave the others, you can do

mask = isnan(DD);
mask(1:end-5, :) = false; % Ignore all up to the 6th row from the bottom by setting the mask to false there.
DD(mask) = 0;

To set nans to 0 in the first 6 rows:

mask = isnan(DD);
mask(7:end, :) = false; % Ignore all rows after the 6th row.
DD(mask) = 0;

Or to do the first 6 and last 6 all in one operation:

mask = isnan(DD);
mask(7:end-5, :) = false; % Ignore middle rows.
DD(mask) = 0;

[Gabriel Luca Pugliese Borges]

Perfect, my friend. Thanks a lot for your help, appreciate it!