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Re: Re: Hash references and illegal octal digits

by peppiv (Curate)
on Dec 24, 2002 at 16:04 UTC ( #222105=note: print w/ replies, xml ) Need Help??


in reply to Re: Hash references and illegal octal digits
in thread Hash references and illegal octal digits

Ah, yes. You is the genius!

Works great mon!

Supa Thanx,

and Happy Holidays!

peppiv


Comment on Re: Re: Hash references and illegal octal digits
Re: Re: Re: Hash references and illegal octal digits
by peppiv (Curate) on Dec 24, 2002 at 20:02 UTC
    Oops! One more breakdown. It appears the code
    my %hash = map { chomp; split /,/ } @array;
    doesn't play well with this data.

    __DATA__ 1001,choochoo 1002,candycane 1003,sockpuppet 1004,choochoo 1005,candycane 1006,sockpuppet6 1007, 1008,bar 0001,choochoo 0002,candycane 0003,sockpuppet 0109,choochoo

    Where 1007 doesn't have any value. I have no idea how to treat this. Does anyone have any ideas?

    peppiv

      Just ensure that there is something after the comma... even if it is a space.
      If you have no control over the data then perhaps try something like this:
      my %hash = map { s/,\n/, \n/; chomp; split /,/ } @array;

      It is usually considered bad form to modify $_ during a map{} operation. People expect map{} to create a new list from an existing list, without modifying the existing list.

      The expression can be written out clearer, more accurately, and using less intermediate memory by using the following code instead:

      my %hash; for (@array) { if (/^([^,]+)(?:,(.*))?$/) { $hash{$1} = $2; } }

      This also has the side effect of handling the case where the input takes the form "1009," or "1009". For "1009," the key will map to an empty string. For "1009" the key will map to the undefined value.

      The regular expression removes the need for chomp() as the $ at the end of the regular expression will not swallow the "\n".

      If efficiency is the true goal, the following code has the exact same effect:

      my %hash; /^([^,]+)(?:,(.*))?$/s && ($hash{$1} = $2) for @array;

      If a few CPU ticks can be spared, the former is far more preferable to the latter.

      my %hash = map { chomp; split /,/,$_,2 } @array;

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