[Tutor] Compute data usage from log
cwitts at compuscan.co.za
Tue Oct 27 12:56:57 CET 2009
bibi midi wrote:
> #!/usr/bin/env python
> # -*- coding: utf-8 -*-
> Calculate internet data consumption
> of service provider
> Code as per help of python tutor mailing list
> Created: 26-Oct-2009
> intro = raw_input('press enter to view your internet data consumption: ')
> log_file = '/home/bboymen/mobily.data.plan'
> total_consumed = 0
> for line in open(log_file):
> total_consumed += int(line.split(' '))
> total_consumed = total_consumed/1000000.0
> print "total data consumed is: %0.3f MB\n" % total_consumed
> #1) show the list comprehension alternative method
> #2) add exception handling e.g. when log_file cant be found or when key interrupt is pressed
> # or when index is not a number, etc
> #3) print latest date of calculated data
> I'm working on TODO no. 3 e.g. I want to show the latest date when
> wvdial generated the ppp data. This is normally the date of last line
> of the ppd:
> Oct 14 11:03:45 cc000002695 pppd: Sent 3489538 bytes, received
> 43317854 bytes.
> For the exception handling i *think* i just use the general exception
> method e.g. will catch all kinds of error. I really dont know what
> other errors will show up aside from the ones i listed in the TODO.
> Advise is appreciated.
> On Mon, Oct 26, 2009 at 2:12 PM, Luke Paireepinart
> <rabidpoobear at gmail.com <mailto:rabidpoobear at gmail.com>> wrote:
> On Mon, Oct 26, 2009 at 3:20 AM, Christian Witts
> <cwitts at compuscan.co.za <mailto:cwitts at compuscan.co.za>> wrote:
> fInput = open('/path/to/log.file', 'rb')
> total_usage = 0
> for line in fInput:
> total_usage += int(line.split(' ').strip())
> print total_usage
> It's actually bad to assign a variable to the file object in this
> case (flinput = ....) because Python will automatically close a
> file after you're done with it if you iterate over it directly,
> but if you include a reference it will stay open until the python
> program ends or you explicitly call flinput.close(). It doesn't
> matter much in this example but in general it is good practice to
> 1) call foo.close() immediately after you're done using a file
> object, or
> 2) don't alias the file object and just over it directly so Python
> will auto-close it.
> Therefore a better (and simpler) way to do the above would be:
> total_usage = 0
> for line in open('/path/to/log.file'):
> total_usage += int(line.split(' '))
> Also note you don't need to strip the input because int() coersion
> ignores whitespace anyway. And additionally you shouldn't be
> opening this in binary mode unless you're sure you want to, and
> I'm guessing the log file is ascii so there's no need for the
> 'rb'. (reading is default so we don't specify an 'r'.)
> And since I like list comprehensions a lot, I'd probably do it
> like this instead:
> total_usage = sum([int(line.split(' ')) for line in
> Which incidentally is even shorter, but may be less readable if
> you don't use list comprehensions often.
> Also, the list comprehension version is likely to be more
> efficient, both because of the use of sum rather than repeated
> addition (sum is implemented in C) and because list comprehensions
> in general are a tad faster than explicit iteration, if i recall
> correctly (don't hold me to that though, I may be wrong.)
> Of course this has no error checking and or niceties, but I
> will leave that up to you.
> The same applies to my modifications.
> Good luck, and let us know if you need anything else!
> Best Regards,
* Not finding the log file would be IOError.
* Casting an alphanumeric or alpha string to integer would be a
ValueError, in this context you won't have a None so you shouldn't need
to worry about a TypeError
* Selecting the 10th element in your list can raise an IndexError if
your line did not contain enough delimiters to create a large enough list.
1MB = 1,024KB = 1,024*1,024B
So your total consumed should be div (1024*1024.0) or div 1048576.0
For the date you can look at the time module to get a nice string
representation of the date/time. Or as you said you want the last date
listed in the log file then you could add something like
for line in open(log_file):
last_log_date = ' '.join(line.split(' ')[:3]
which would take the first 3 elements in your list and combine them
again. Of course this is again just a simple representation of what to do.
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