Ryan Frantz wrote:
>> Here is one way to approach:
>> !perl
>>
>> use strict;
>> use warnings;
>>
>> my %AlphaToNbr = qw(jan 1 feb 2 mar 3 apr 4 may 5 jun 6 jul 7 aug 8
>> sep 9 oct 10 nov 11 dec 12); foreach my $MySortedFile (sort {
>> $a->[1] <=> $b->[1]
>> or
>> $AlphaToNbr{lc($a->[2])} <=>
> $AlphaToNbr{lc($b-
>>> [2])} or
>> $a->[3] <=> $b->[3]
>> }
>> map {[$_, /^.(\d{4})(\w{3})(\d{2})/]}
>> <DATA> ) {
>> chomp($MySortedFile->[0]);
>> print $MySortedFile->[0] . "\n";
>> }
>>
>
> I have a rudimentary understanding of the above now (from reading Ch
> 15 of 'Learning Perl' and the perlreftut manpage). This is what I
> grok (assuming a YYYYmmmDD format):
>
> 1. Create a hash with numeric equivalents for the months.
> 2. Perform a sort by first comparing numbers (I'm assuming the YYYY,
> but I don't quite know how that reference works).
The (\d{4}) implies numeric and there MUST be four digits(the form can
be {lowest char count,highest character count). If you leave blank like {1,}
then says 1 to as many as you can find.
> 3. Then comparing mmm (having been converted to lower case, the value
> of the respective AlphaToNbr key is compared).
> 4. Compare another pair of numbers (DD?)
Correct if the year is equal and the month is equal then compare the
days.
>
> After that I'm lost. I'm not familiar with the 'map' function or what
> happens after that.
>
> Also, you use an imaginary scalar that would contain the data. I have
> the data in an array and tried to use your sortsub as follows (taking
> some cues from the LP book); I think I'm off base...
>
> ----begin snip----
> (omitted creation of array @user_links)
> my %AlphaToNumber = (
> jan => "1",
> feb => "2",
> mar => "3",
> apr => "4",
> may => "5",
> jun => "6",
> jul => "7",
> aug => "8",
> sep => "9",
> "oct" => "10",
> nov => "11",
> dec => "12",
> );
>
> # sort chronologically using a code snippet from 'Wags'
> @user_links = ( sort {
> $a->[1] <=> $b->[1]
> or
> $AlphaToNumber{lc($a->[2])} <=> $AlphaToNumber{lc($b->[2])}
> or
> $a->[3] <=> $b->[3]
> } @user_links;
> map {[$_, /^.(\d{4})(\w{3})(\d{2})/]}
> <DATA> );
Just take <DATA> and replace that with @user_links. The code should
look like:
@user_links = ( sort {
$a->[1] <=> $b->[1]
or
$AlphaToNumber{lc($a->[2])} <=> $AlphaToNumber{lc($b->[2])}
or
$a->[3] <=> $b->[3]
}
map {[$_, /^.(\d{4})(\w{3})(\d{2})/]}
@user_links;
The map is creating an array reference where
item 0 is Capturing the whole input line
item 1 is the (\d{4}) Capturing the year
item 2 is the (\w{3}) Capturing the month
item 3 is the (\d{2}) Capturing the day
Now as you view the sort you see the $a->[1] <=> $b->[1] which is comparing the
year then [2] is comparing the numeric month then [3] is comparing the numeric
day
Wags ;)
> ----end snip----
>
>> __DATA__
>> /2005Jul01-2005Jul02/foo/bar.html
>> /2005Jul05-2005Jul06/foo/bar.html
>> /2005Jun09-2005Jun10/foo/bar.html
>> /2005Jun10-2005Jun11/foo/bar.html
>> /2005Jun13-2005Jun14/foo/bar.html
>> /2005Jun14-2005Jun15/foo/bar.html
>>
>> Output:
>> /2005Jun09-2005Jun10/foo/bar.html
>> /2005Jun10-2005Jun11/foo/bar.html
>> /2005Jun13-2005Jun14/foo/bar.html
>> /2005Jun14-2005Jun15/foo/bar.html
>> /2005Jul01-2005Jul02/foo/bar.html
>> /2005Jul05-2005Jul06/foo/bar.html
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