python grep

Stefan Behnel stefan_ml at behnel.de
Thu Apr 8 17:40:36 CEST 2010


Mag Gam, 08.04.2010 14:21:
> On Thu, Apr 8, 2010 at 7:31 AM, Stefan Behnel wrote:
>> Mag Gam, 08.04.2010 13:21:
>>>
>>> I am in the process of reading a zipped file which is about 6gb.
>>>
>>> I would like to know if there is a command similar to grep in python
>>> because I would like to emulate, -A -B option of GNU grep.
>>>
>>> Lets say I have this,
>>>
>>> 083828.441,AA
>>> 093828.441,AA
>>> 094028.441,AA
>>> 094058.441,CC
>>> 094828.441,AA
>>> 103828.441,AA
>>> 123828.441,AA
>>>
>>>
>>> if I do grep -A2 -B2 "CC"
>>>
>>> I get 2 lines before and 2 lines after "C"
>>>
>>> Is there an easy way to do this in python?
>>
>> Sure, just use a sliding window.
>>
>> However, for a 6BG file, you won't really like the performance. It's
>> basically impossible to beat the speed of (f)grep.
>>
>> I'd use the subprocess module to run zfgrep over the file and parse the
>> output in Python.
>>
> Oh, thats nice to know!
>
> But I use the CSV module with gzip module. Is it still possible to do
> it with the subprocess?

Depends on what you do with the csv module and how it interacts with the 
search above. Giving more detail may allow us to answer your question and 
to provide better advice.

Stefan




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