Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

I generated 500,000 lines of random CSV with this script

#!/usr/bin/perl use strict; use warnings; # create source numbers if they don't exist my $many = 500000; my $source='numbers.csv'; open CSV, '>', $source or die "can't write to $source: $!\n"; for (1..$many) { my @numbers; push @numbers, (int rand 1000) for (1..5); print CSV join ",",@numbers; print CSV $/; }

Then I tried a few one liners to sum the columns, I ran each twice and post the second timing to allow for cache

nph>time cat numbers.csv | perl -nle'@d=split /,/;$a[$_]+=$d[$_] for ( +0..4);END{print join "\t", @a}' 249959157 249671314 249649377 250057435 249420 +634 real 0m17.10s user 0m15.46s sys 0m0.08s nph>time perl -nle'my @d=split /,/;$a[$_]+=$d[$_] for (0..4);END{print + join "\t", @a}' numbers.csv 249959157 249671314 249649377 250057435 249420 +634 real 0m13.71s user 0m12.77s sys 0m0.04s nph>time perl -nle'my($a,$b,$c,$d,$e)=split /,/;$ta+=$a, $tb+=$b, $tc+ +=$c, $td+=$d, $te+=$e;END{print join "\t", $ta,$tb,$tc,$td,$te}' numb +ers.csv 249959157 249671314 249649377 250057435 249420 +634 real 0m6.45s user 0m5.91s sys 0m0.07s

The last one was consistently faster after several attempts with it and the second.


Pereant, qui ante nos nostra dixerunt!

In reply to Re: Efficient way to sum columns in a file by Random_Walk
in thread Efficient way to sum columns in a file by sk

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    [ambrus]: erix: further, SQLite may be the second most installed piece of software on earth after zlib.
    [erix]: heh, really? yeah, I suppose it may be so
    [ambrus]: We're not really sure. There are some other contenders like libjpeg, and it's not easy to tell how you even measure this.
    [ambrus]: But we figured it's close.

    How do I use this? | Other CB clients
    Other Users?
    Others surveying the Monastery: (9)
    As of 2017-09-25 14:18 GMT
    Find Nodes?
      Voting Booth?
      During the recent solar eclipse, I:

      Results (280 votes). Check out past polls.