[Tutor] A Really Quick Question
kent37 at tds.net
Sat Oct 22 17:57:17 CEST 2005
Steve Haley wrote:
> I am running Python 2.1 which ships with ArcView 9.1. I am going
> through the 2.1 tutorial and came across readlines().
> The tutorial seems to be telling me that ‘f.readlines(2) should read out
> 2 bytes plus what is needed to complete the current line. Instead, it
> is reading out the entire file no matter what I enter as a parameter. I
> know I am going to feel really dumb when I hear the explanation but
> please remember I’m new to this.
As the documentation says, the parameter to readlines() is a hint which may be rounded up to an internal buffer size. Python 2.4 seems to use a buffer size of 8192 so using sizehint < 8192 may have no effect.
If you want to read a single line of the file, use readline() instead. To iterate through all the lines of a file one at a time use
for line in f.xreadlines():
# process line
HTH. Come back if you have more questions!
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