Organize large DNA txt files

[thomasvangurp at gmail.com]

Dear Fellow programmers,

I'm using Python scripts too organize some rather large datasets
describing DNA variation. Information is read, processed and written
too a file in a sequential order, like this
1+
1-
2+
2-

etc.. The files that i created contain positional information
(nucleotide position) and some other info, like this:

file 1+:
--------------------------------------------
1	73	0	1	0	0
1	76	1	0	0	0
1	77	0	1	0	0
--------------------------------------------
file 1-
--------------------------------------------
1	74	0	0	6	0
1	78	0	0	4	0
1	89	0	0	0	2

Now the trick is that i want this:

File 1+ AND File 1-
--------------------------------------------
1	73	0	1	0	0
1	74	0	0	6	0
1	76	1	0	0	0
1	77	0	1	0	0
1	78	0	0	4	0
1	89	0	0	0	2
-------------------------------------------

So the information should be sorted onto position. Right now I've
written some very complicated scripts that read a number of lines from
file 1- and 1+ and then combine this output. The problem is of course
that the running number of file 1- can be lower then 1+, resulting in
a incorrect order. Since both files are too large to input in a
dictionary at once (both are 100 MB+) I need some sort of a
alternative that can quickly sort everything without crashing my pc..

Your thoughts are appreciated..
Kind regards,
Thomas