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Remove repetitions in Array

Discussion in 'Perl' started by oleber, Apr 28, 2007.

  1. oleber

    oleber New Member

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    The normal idea is to have an hash table, iterate over the array and using the elements as keys.

    Something like ::(
    Code:
    my @array = (1,5,3,7,9,1,4,5,7,6,7);
    
    my %hash;
    
    foreach my $element (@array) {
    	$hash{$element}++
    }
    
    my @arrayNoRep = keys %hash;
    print join(", ", @arrayNoRep);
    Lets simplify the loop :cool:
    Code:
    my @array = (1,5,3,7,9,1,4,5,7,6,7);
    
    my %hash;
    $hash{$_}++ foreach @array;
    
    my @arrayNoRep = keys %hash;
    print join(", ", @arrayNoRep);
    But do we need the loop? :confused:
    Code:
    my @array = (1,5,3,7,9,1,4,5,7,6,7);
    
    my %hash;
    @hash{@array} = ();
    
    my @arrayNoRep = keys %hash;
    print join(", ", @arrayNoRep);
    And throwing away the hash defeniton. :eek:
    Code:
    my @array = (1,5,3,7,9,1,4,5,7,6,7);
    
    my @arrayNoRep = keys %{{map {$_=>0} @array}};
    
    print join(", ", @arrayNoRep);
    I love this one line in Perl.:D
     
  2. pradeep

    pradeep Team Leader

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    That's really cool! :D
     
  3. oleber

    oleber New Member

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  4. msmani_1980

    msmani_1980 New Member

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    Remove repetitions in Array without loop

    Code:
    my @array = (1,5,3,7,9,1,4,5,7,6,7);
    @t{@array}=();
    print join sort keys %t,",";
    Result : 1, 3, 4, 5, 6, 7, 9
     
  5. oleber

    oleber New Member

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    So, What did you add to the subject msmani_1980?
     
  6. PradeepKr

    PradeepKr New Member

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    I couldn't get this line in the 3rd code block
    @hash{@array} = ();

    hash is defined with % in the previous line (%hash) and then it is seen with @ which is meant for array. Can somebody explain me, what exactly "@", prepended to hashname, does?
     
  7. pradeep

    pradeep Team Leader

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    "@", prepended to hashname means we are accessing a hash slice i.e. a group of elements instead of one element a time.
     

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