Inserting if loop within awk - bash

Question

I had a problem solved in a previous post using the awk, but now I want to put an if loop in it, but I am getting an error.
Here's the problem:
I had a lot of files that looked like this:
Header
175566717.000
175570730.000
175590376.000
175591966.000
175608932.000
175612924.000
175614836.000
.
.
.
175680016.000
175689679.000
175695803.000
175696330.000
And I wanted to extract the first 2000 lines (line 1 to 2000), then extract the lines 1500 to 3500, then 3000 to 5000 and so on... What I mean is: extract a window of 2000 lines with an overlap of 500 lines between contiguous windows until the end of the file.
This is the awk command used for it:
awk -v i=1 -v t=2000 -v d=501 'NR>1{a[NR-1]=$0}END{
while(i<NR-1){
++n;
for(k=i;k<i+t;k++)print a[k] > "win"n".txt";
close("_win"n".txt")
i=i+t-d
}
}' myfile.txt
done
And I get several files with names win1.txt , win2.txt , win3.txt , etc...
My problem now is that because the file was not a multiple of 2000, my last window has less than 2000 lines. How can I put an if loop that would do this: if the last window had less than 2000 digital numbers, the previous window should had all the lines until the end of the file.
EXTRA INFO
When the windows are created, there is a line break at the end.That is why I needed the if loop to take into account a window of less than 2000 digital numbers, and not just lines.

Answer 1

If you don't have to use awk for some other reason, try the sed approach
#!/bin/bash
file="$(sed '/^\s*$/d' myfile.txt)"
sed -n 1,2000p <<< "$file"
first=1500
last=3500
max=$(wc -l <<< "$file" | awk '{print $1}')
while [[ $max -ge 2000 && $last -lt $((max+1500)) ]]; do
sed -n "$first","$last"p <<< "$file"
((first+=1500))
((last+=1500))
done
Obviously this is going to be less fast than awk and more error prone for gigatic files, but should work in most cases.

Answer 2

Change the while condition to make it stop earlier:
while (i+t <= NR) {
Change the end condition of the for loop to compensate for the last output file being potentially bigger:
for (k = i; k < (i+t+t-d <= NR ? i+t : NR); k++)
The rest of your code can stay the same; although I took the liberty of removing the close statement (why was that?), and to set d=500, to make the output files really overlap by 500 lines.
awk -v i=1 -v t=2000 -v d=500 'NR>1{a[NR-1]=$0}END{
while (i+t <= NR) {
++n;
for (k=i; k < (i+t+t-d <= NR ? i+t : NR); k++) print a[k] > "win"n".txt";
i=i+t-d
}
}' myfile.txt
I tested it with small values of t and d, and it seems to work as requested.
One final remark: for big input files, I wouldn't encourage storing the whole thing in array a.