in reply to Re^4: question about what to grep(?)
in thread question about what to grep(?)
As always, there is more than one way to do it. Please see code below for some illustrations. Some comments:
use strict; use warnings; use Math::Round qw/round/; use Data::Dumper; # function returns 1 if all arguments are integer # zero otherwise sub is_approximately_an_integer { my $eps = 0.0001; while( my $x = shift ) { # need to use "round", "int" does not work! return 0 if abs( $x-round($x) ) > $eps; } return 1 } # some test cases print "Testing...\n"; print is_approximately_an_integer( 1, 3.99999999, 5 ), "\n"; print is_approximately_an_integer( 1.2, 3.99999999, 5 ), "\n"; print is_approximately_an_integer( 1, 3.99999999, 5.0000001 ), "\n"; print is_approximately_an_integer( 1, 3.99999999, -5 ), "\n"; print is_approximately_an_integer( 1, 3.99999999, -5.1 ), "\n"; print is_approximately_an_integer( 1, 3.99999999, -5.000000001 ), "\n" +; print is_approximately_an_integer( 1, -3.99999999, -5.000000001 ), "\n +"; print is_approximately_an_integer( 1 ), "\n"; print is_approximately_an_integer( 1.5 ), "\n"; # what if we have hash of arrays ? my %hash = ( "1,2,3" => [ 1, 3.99999999, 5 ], "1,2,4" => [ 1.2, 3.99999999, 5 ], "1,2,5" => [ 1, 3.99999999, 5.0000001 ], # etc ); # this returns only the arrays but lose keys print "\nSelected arrays\n"; my @wants = grep { is_approximately_an_integer( @$_ ) } values %hash; print Dumper( @wants ); # this returns the keys print "\nSelected keys...\n"; my @wants = grep { is_approximately_an_integer( @{$hash{$_}} ) } keys +%hash; print Dumper( @wants ); print "...and the associated array.\n"; # and you can get the arrays as well print Dumper( @hash{@wants} );
|
|---|