comment on

For the "simple" case where you have all files in strict time-sequential order:

use Modern::Perl;

open my $FILEA, '<', './FILEA.TXT' or die $!;
open my $FILEB, '<', './FILEB.TXT' or die $!;
open my $FILEC, '<', './FILEC.TXT' or die $!;
open my $FILED, '<', './FILED.TXT' or die $!;

my $ts_B = 0;
my $ts_C = 0;
my $ts_D = 0;
while ( my $ts_A = <$FILEA> ) {
    chomp $ts_A;
    say "A:$ts_A matches B:$ts_B" if $ts_A == $ts_B;
    while ( $ts_B = <$FILEB> ) {
        chomp $ts_B;
        last if $ts_B > $ts_A;
        next if $ts_B < $ts_A;
        say "A:$ts_A matches B:$ts_B";
    }
    say "A:$ts_A matches C:$ts_C" if $ts_A == $ts_C;
    while ( $ts_C = <$FILEC> ) {
        chomp $ts_C;
        last if $ts_C > $ts_A;
        next if $ts_C < $ts_A;
        say "A:$ts_A matches C:$ts_C";
    }
    say "A:$ts_A matches D:$ts_D" if $ts_A == $ts_D;
    while ( $ts_D = <$FILED> ) {
        chomp $ts_D;
        last if $ts_D > $ts_A;
        next if $ts_D < $ts_A;
        say "A:$ts_A matches D:$ts_D";
    }
}
[download]

Output

A:102 matches B:102
A:264 matches C:264
A:403 matches D:403
A:403 matches D:403
A:560 matches D:560
A:560 matches D:560
A:744 matches B:744
A:744 matches B:744
A:827 matches C:827
A:915 matches D:915
A:915 matches D:915
A:1018 matches C:1018
A:1180 matches D:1180
...
[download]

The files I used don't have timestamps, just random numbers in an ever increasing sequence, but the logic remains the same.

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

My blog: Imperial Deltronics

In reply to Re: matching datetimestamps and concatenating data where timestamps match from multiple large datafiles by CountZero
in thread matching datetimestamps and concatenating data where timestamps match from multiple large datafiles by Cosmic37

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