[Tutor] large file

[cristeto1981]

Alan Gauld wrote:
> 
> 
> "Hs Hs" <ilhs_hs at yahoo.com> wrote
> 
>> I have a very large file 15Gb.
> 
>> Every two lines are part of one readgroup.
>> I want to add two variables to every line.
> 
>> HWUSI-EAS1211_0001:1:1:977:20764#0   RG:Z:2301
>> HWUSI-EAS1211_0001:1:1:977:20764#0    RG:Z:2302
>> ...
>> Since I cannot read the entire file, I wanted to cat the file
> 
> What makes you think you cannot read the entire file?
> 
>> something like this:
>>
>> cat myfile  | python myscript.py > myfile.sam
> 
> How does that help over Python reading the file line by line?
> 
>> I do not know how to execute my logic after I read the line, 
>> althought I tried:
> 
>> while True:
>>        second = raw_input()
>>        x =  second.split('\t')
> 
> Why are you splitting theline? You only need to append
> data to the end of the line...
> 
>> Could someone help me here either what I want to do.
> 
> In pseudo code:
> 
> open input and ouput files
> read the first 14 lines from input
> oddLine = True
> while True:
>      read line from input
>      if oddLine:
>             append odd data
>      else
>            append evenData
>      write line to output file
>      oddLine = not oddLine
> 
> You probably want a try/except in there to catch the end of file.
> 
> 
> This is not very different from the menu example in the file
> handling topic of my tutorial...
> 
> HTH
> 
> -- 
> Alan Gauld
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
> 
> 
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> To unsubscribe or change subscription options:
> http://mail.python.org/mailman/listinfo/tutor
> 
> 
Thanks for this thread. This is very helful. I'm learning a lot from you
guys. :)

-----
[url=http://crosspromotion.wizard4u.com/]joint ventures[/url]

-- 
View this message in context: http://old.nabble.com/-Tutor--large-file-tp28874185p28878191.html
Sent from the Python - tutor mailing list archive at Nabble.com.