Ted, Holli & jZed,

Thanks a lot for your help. I am bothering you one more time, sorry!
The sample file i posted earlier is different from actual one.
I just wanted to get a hint from you guys and learn things to apply on my own but later when i tried to implement on my real file, i couldn't find a way.

Actually i am unable to create a matching pattern statement
for my hash. Please help me here with the real file which
looks like:

0.000000e+000 1.502947e+000
1.162272e-012 1.508957e+001
2.324544e-012 1.508948e+000
.....
0.000000e+000 1.502947e+001
1.162272e-012 1.508941e+001
2.324544e-012 1.508940e+000
....
0.000000e+000 1.503947e+000
1.162272e-012 1.504947e+000
2.324544e-012 1.508900e+001
..... so on

Its a 300MB file, the two values are tab seperated. The first column value is repeating after lets say 2000 lines. Their pair value varies (could be the same)
I would appreciate if you write a precise comments especially on matching statement

Thanks in advance.
Syed.