Not tested this, run it (or some derivation thereof) over the output to get
increasing randomness.
You will want to keep max_buffered_lines as high as possible really I
imagine. If shuffle() is too intensize
you could itterate over the buffer several times randomly removing and
printing lines until the buffer is empty/suitibly small removing some more
processing overhead.
### START ###
import random
f = open('corpus.uniq')
buffer = []
max_buffered_lines = 1000
for line in f:
if len(buffer) < max_buffered_lines:
buffer.append(line)
else:
buffer.shuffle()
for line in buffer:
print line
random.shuffle(buffer)
for line in buffer:
print line
f.close()
### END ###
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of
Joerg Schuster
Sent: 07 March 2005 13:37
To: python-list@python.org
Subject: shuffle the lines of a large file
Hello,
I am looking for a method to "shuffle" the lines of a large file.
I have a corpus of sorted and "uniqed" English sentences that has been
produced with (1):
(1) sort corpus | uniq > corpus.uniq
corpus.uniq is 80G large. The fact that every sentence appears only
once in corpus.uniq plays an important role for the processes
I use to involve my corpus in. Yet, the alphabetical order is an
unwanted side effect of (1): Very often, I do not want (or rather, I
do not have the computational capacities) to apply a program to all of
corpus.uniq. Yet, any series of lines of corpus.uniq is obviously a
very lopsided set of English sentences.
So, it would be very useful to do one of the following things:
- produce corpus.uniq in a such a way that it is not sorted in any way
- shuffle corpus.uniq > corpus.uniq.shuffled
Unfortunately, none of the machines that I may use has 80G RAM.
So, using a dictionary will not help.
Any ideas?
Joerg Schuster
--
http://mail.python.org/mailman/listinfo/python-list
--
http://mail.python.org/mailman/listinfo/python-list
