big job, starting with little script

[rdettwyler]

Greetings, oh wise ones. I need to create a hash to process several million records (am building competitor to Google (yes, I am a dreamer)). I need to process something like this: file FOO contains single-field records of fruits and vegetables, and file BAR contains the arrays.

$cat foo
apple
apple
pear
pear
zucchini
zucchini
eggplant
eggplant
potato
potato

$cat bar
#!/usr/bin/perl
$map{'apple'} = 'fruit';
$map{'pear'} = 'fruit';
$map{'zucchini'} = 'vegetable';
$map{'eggplant'} = 'vegetable';
$map{'potato'} = 'vegetable';

open FILE, "foo" or die$!;
my @lines = <FILE>;

while (my $line = <FILE>)
{
chomp;
print "$map($_)\n";

Why does this give me nothing? I want to see this:

apple fruit
apple fruit
pear fruit
pear fruit
zucchini vegetable
zucchini vegetable
zucchini vegetable
eggplant vegetable
eggplant vegetable
eggplant vegetable
potato vegetable
potato vegetable

Thank you so much. Your humble servant, RickyD

[zek152]

Your problem is that you slurp in the file with "my @lines = <FILE>;" This means that it will never enter the while loop (<FILE> will return undef). Simply take that line out. Also chomp works on $_ but you have $line = <FILE>. The following should work:

while (<FILE>)
{
    chomp;
    print "$_ $map{$_}\n";
}

It looks like you have a missing "}" to close the while loop. Also you should close your FILE filehandle at the end of the program. Its a good habit. Hope that helps.

[Roy Johnson]

You're [also] looking up $_, but reading into $line. Try

while(<FILE>)

instead.

[muba]

Try to find out where you put the line after reading from the file. Is it in $line (as $line = <FILE>) would suggest?

Or is it in $_, where you seem to think it is, judging by your use of chomp with no further arguments and thusly implying chomp $_.

And even more explicitely in the part where you try to print "$map($_)";

That print statement brings us to another point - you're using parens here, not accolades, or curly braces. Keep an eye out for that kind of typo :)

The interesting thing is that neither answer is true, as has been pointed out above me, due to you slurping in the entire file before the while loop.

But I'd like to point out something else as well. I don't mean to discourage you but I think your approach deserves some further thought. Tomato: fruit or veggie?

[fullermd]

But I'd like to point out something else as well. I don't mean to discourage you but I think your approach deserves some further thought. Tomato: fruit or veggie?

Well, fruit, obviously. To a biologist, anyway. But then, so are zucchini and eggplant, right?

[Generoso]

You may what to take a look at this.

#!/usr/bin/perl
use strict;
use warnings;

#open FILE, "foo" or die$!;
#my @lines = <FILE>;
my %map=();
my $datapos = tell DATA;
foreach (grep(/,/, <DATA>))
{
    chomp;
    my ($p1,$p2) = split /,/,$_;
    $map{$p1} = $p2;
    print '$map{',$p1,'} = \'',$map{$p1},"';\n";
}
seek DATA, $datapos, 0;
foreach (grep(!/,/, <DATA>))
{
    chomp;
    print "$_ $map{$_}\n";
}

__DATA__
apple,fruit
pear,fruit
zucchini,vegetable
eggplant,vegetable
potato,vegetable
apple
apple
pear
pear
zucchini
zucchini
eggplant
eggplant
potato
potato