in reply to Re^2: Compare fields in a file
in thread Compare fields in a file

Easy, in my script, add 
sort {
    $b->[2] <=> $a->[2]
}

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between the first map and the grep.

The output will now be sorted by descending amplitude and you will have only one entry per second.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

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Re^4: Compare fields in a file
by honyok (Sexton) on Feb 10, 2009 at 23:07 UTC
    Thanks gentlefolk. Great ideas!
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Re^4: Compare fields in a file
by honyok (Sexton) on Feb 11, 2009 at 05:10 UTC
    Elegant. I think I see how your code tests for each second, 
    $date =~ m/(\d{2})-(\d{2})-(\d{4}) (\d{2}:\d{2}:\d{2})/;

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    but my goal is to filter based on any arbitrary time increment(+/-1s,+/-5s,+/-300ms,...).

    Re Grandfather's comments: The ultimate point of this exercise is to avoid MS Excel monkeying with my time stamps. I have files with thousands of data points, each with many numerical attributes(x,y,z,date,time,magnitude,...). I would like to adapt a solution to sort and/or filter based on any or all of the attributes - time being the most difficult. Anything done outside of Excel saves time and aggravation.
    - honyok
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      That can certainly be done. All you have to do is to replace the last map block by something like: 
      map {
    ($date, $magnitude) = (split',')[3,4];
    [$_, normalize($date), $magnitude]
}

      [download]
      Then you add a subroutine normalize which transforms your date-time string into a value (string or numerical) which has the same value for each "slot". For instance: 
      sub normalize {
    my $value = shift;
    my ($hours, $minutes, $seconds) = $value =~ m/(\d{2}):(\d{2}):(\d{
+2}\.\d{3})$/;
    return int((1000 * $seconds + $minutes * 60 + $hours * 3600)/300);
}

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      As we now get a numeric result and not a string, we also have to replace the cmp in the sort block by a <=> to have the sort work correctly.

      With a little effort you can further parametrize the subroutine so you can define the "slot" in a more flexible way without having to rewrite the sub every time.

      CountZero

      A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

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