One could use a buffer of the desired size of data, and then store the data to be averaged cycling through the buffer. As I cannot replicate your data, I am using random numbers to demonstrate the principle: 

use strict;
use warnings;

# initialize averaging
use List::Util 'sum';
my $size = 10;
my @store;
my $i = -1;

while (1){
  my $line_count = int rand 100;

  # store data and output average
  $store[ ($i+=1) %= $size ] = $line_count;
  my $average = sum( grep defined, @store )/$size;
  print "Average line count: $average\n";
}

[download]

This way, one would always print the average of the last $size numbers generated. It requires a run up period, so one cannot trust the first $size averages, which I would guess, should not be an issue if you want to run it for a long time.

In reply to Re: Reading the average of a changing varible by hdb
in thread Reading the average of a changing varible by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.