[Tutor] Simple Question...
R. Alan Monroe
amonroe at columbus.rr.com
Sat Oct 16 22:52:16 CEST 2004
> This will work perfectly if your file is small enough to fit in your
> computer's memory. If you want a function that does this on large
> files, you'll have to use something in those lines:
> import random
> def randomLineFromBigFile(fileName, numLines):
> whatLine = random.randint(1, numLines) # choose a random line number
> source = open(fileName, 'r')
> i = 0
> for line in source:
> i += 1
> if i == whatLine: return line
> return None
> This function uses very little (and a constant amount of) memory. The
> downside is that you have to know the total number of lines in the file
> (that's the numLines argument) before calling it. It's not a very hard
> thing to do.
Wouldn't it be much quicker to do something like this?
size = os.path.getsize('test.txt')
randline = random.randint(1, size)
testfile = open('test.txt', 'r')
print testfile.readline() #read what is likely half a line
print testfile.readline() #read the next whole line
You'd just need to add some exception handling in the event you tried
to read off the end of the file.
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