Have you looked at map? What parts of it do you have problems with? What else have you tried, and how did it fail?

@x = map { if ($_ > 1) { 1 } } (-5 .. 5)
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@x = map { if ($_ > 1) { 1 } else { 0 } } (-5 .. 5)
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@x = map { $_ > 1 ? 1 : 0 } (-5 .. 5)
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Just to elaborate a little.  You can also leave off the else branch, in which case map would return the empty string (not sure why not undef) when the if-condition isn't true:

my @x = map { if ($_ > 0) { $_*2 } } (-2 .. 2);
use Data::Dumper;  print Dumper \@x;

__END__
$VAR1 = [
          '',
          '',
          '',
          2,
          4
        ];
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When you don't want to return anything in those cases, you can use the empty list ():

my @x = map { if ($_ > 0) { $_*2 } else { () } } (-2 .. 2);
# or: my @x = map { $_ > 0 ? $_*2 : () } (-2 .. 2);
use Data::Dumper;  print Dumper \@x;

__END__
$VAR1 = [
          2,
          4
        ];
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You can also leave off the else branch, in which case map would return the empty string (not sure why not undef) when the if-condition isn't true...     (Emphasis added)

See Re: Map Function Weirdness and Re: Map Function Weirdness (and ikegami's elaboration thereto Re^2: Map Function Weirdness) to Map Function Weirdness.