Hi. I need to manipulate some data to big for excel, sorting it and
extracting data in Python. sample data follows. Each line has
coordinates, 2 values in 2 columns. The coordinates for line one are
chr2L 9674997. The score for this line is in the last
tab-delineated column and is equal to 0.10. For every line I need to
convert that score from a log value to an integer (from -4.0 to 4.0 to
a number from 1 to 1000), and then I need to filter the data so that
the only lines remaining are those who have two consecutive lines with
scores in the top 25th percentile. So the data needs to be sorted
first to get that consecutive thing, first by chromosome (chr2L) and
then by position in column 4 (967499). I want at the end another huge
text file, just like the first but with with the non-qualifying lines
removed. I hope that is easy. Thanks 

chr2L	NS	53zt2	9674997	9675046	0.10	
chr2L	NS	53zt2	5351242	5351291	0.23	
chr2L	NS	53zt2	16228047	16228096	0.23	
chr2L	NS	53zt2	6674892	6674941	0.80	
chr2L	NS	53zt2	3219264	3219313	-0.01	
300000 rows like this.