seeking thru a file
Nils Rüttershoff
nils at ccsg.de
Fri Jun 26 08:00:58 EDT 2009
Hi Mag,
Mag Gam wrote:
> I have a compressed CSV gziped file. I was wondering if it is possible
> to seek thru a file
>
> For example:
>
> I want to load the first 100 lines into an array. Process the data
>
> Seek from 101 line to 200 lines. Process the data (remove lines 0 -
> 100) from memory
>
> Seek 201 to 300 line. Process the data (remove 200-300)) from memory
>
> etc..etc..
>
This would be very easy. Here is one way you could do it:
(I didn't test the code; I've just write it down, assuming you use
python 2.6, cause you didn't mentioned which version you are using...)
import gzip
step = 100
data_present = True
with gzip.open(foo.csv.gzip) as my_file:
counter = 0
my_buffer = []
while data_present:
while counter <= step:
line = my_file.readline()
if line:
my_buffer.append(my_file.readline())
counter += 1
else:
data_present = False
break
if len(my_buffer) > 0:
do_something(my_buffer)
counter = 0
my_buffer = []
Kind Regards, Nils
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