[EMAIL PROTECTED] wrote:
> if it is a medium size to large file, then it is recommended to use
> xreadlines instead of readlines.
> here the example from Python help:
>
> import xreadlines, sys
>
> for line in xreadlines.xreadlines(sys.stdin):
> pass
In recent versions of Python, xreadlines() has become a method of file
objects, so it's unnecessary to import xreadlines:
myfile = open('data.txt', 'r')
for line in myfile.xreadlines():
process(line)
For the O.P.: The difference between readlines() and xreadlines(), is
that readlines() will read the entire file in a single chunk -- if
it's an 11MB file, then you've just filled an 11MB block of memory
(plus a bit more for overhead). But xreadlines() reads in smaller
chunks -- theoretically a single line at a time, but I believe that
it's probably actually buffered in 1024-byte blocks (or something like
that). Both methods, when used in a loop as above, will produce each
line of the file successively. The only difference is that
readlines() will (potentially) use up more memory, while xreadlines()
has a tiny bit more overhead (and, ISTM, more potential for
concurrency issues).
Jeff Shannon
Technician/Programmer
Credit International
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