[Tutor] iteration help

richard kappler richkappler at gmail.com
Thu Aug 20 15:27:02 CEST 2015

Running python 2.7 on Linux

While for and if loops always seem to give me trouble. They seem obvious
but I often don't get the result I expect and I struggle to figure out why.
Appended below is a partial script. Ultimately, this script will read a
log, parse out two times from each line of the log, a time the line was
written to the lg (called serverTime in the script) and an action time from
elsewhere in the line, then get the difference between the two. I don't
want every difference, but rather the average per hour, so I have a line
count. The script will output the average time difference for each hour.
I've got most of the pieces working in test scripts, but I'm stymied with
the single output bit.

The idea is that the script takes the hour from the server time of the
first line of the log and sets that as the initial serverHr. That works,
has been tested. Next the script is supposed to iterate through each line
of the log (for line in f1) and then check that there is a time in the line
(try), and if not skip to the next line. That works, has been tested.

As each line is iterated over, my intent was that the variable newServerHr
(read from the current line) is compared to serverHr and if they are the
same, the script will increase the count by one and add the difference to a
cummulative total then go to the next line. If the newServerHr and serverHr
are not the same, then we have entered a new clock hour, and the script
should calculate averages and output those, zero all counts and cummulative
totals, then carry on. The idea being that out of 117,000 ish lines of log
(the test file) that have inputs from 0200 to 0700, I would get 6 lines of

I've got everything working properly in a different script except I get 25
lines of output instead of 6, writing something like 16 different hours
instead of 02 - 07.

In trying to chase down my bug, I wrote the appended script, but it outputs
117,000 ish lines (times 02-07, so that bit is better), not 6. Can someone
tell me what I'm misunderstanding?

#!/usr/bin/env python

import re

f1 = open('ATLA_PS4_red5.log', 'r')
f2 = open('recurseOut.log', 'a')

# read server time of first line to get hour
first_line = f1.readline()
q = re.search(r'\d\d:\d\d:\d\d', first_line)
q2 = q.start()
serverHr = (first_line[q2:q2+2])

for line in f1:
        s = line
        #    read server time
        a = re.search(r'\d\d:\d\d:\d\d', s)  # find server time in line
        b = a.start()                        # find 1st position of srvTime
        newServerHr = (s[b:b+2])          # what hour is it now?
        if newServerHr != serverHr:
            f2.write('hour ' + newServerHr + '\n')
            serverHr == newServerHr



All internal models of the world are approximate. ~ Sebastian Thrun

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