[Tutor] large file

[Hs Hs]

hi:

I have a very large file 15Gb. Starting from 15th line this file shows the following lines:

HWUSI-EAS1211_0001:1:1:977:20764#0     

HWUSI-EAS1211_0001:1:1:977:20764#0    

HWUSI-EAS1521_0001:1:1:978:13435#0 

HWUSI-EAS1521_0001:1:1:978:13435#0 


Every two lines are part of one readgroup. I want to add two variables to every line. First variable goes to all lines with odd numbers. Second variable should be appended to all even number lines.  like the following:

HWUSI-EAS1211_0001:1:1:977:20764#0   RG:Z:2301

HWUSI-EAS1211_0001:1:1:977:20764#0    RG:Z:2302

HWUSI-EAS1521_0001:1:1:978:13435#0  RG:Z:2301

HWUSI-EAS1521_0001:1:1:978:13435#0  RG:Z:2302

Since I cannot read the entire file, I wanted to cat the file 

something like this:

cat myfile  | python myscript.py > myfile.sam


I do not know how to execute my logic after I read the line, althought I tried:

myscript.py:

while True:
        second = raw_input()
        x =  second.split('\t')
        




Could someone help me here either what I want to do. Or suggesting a different method. 

thanks


      
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