Hi, Say I have an array @a_array

[milage]

Hi,

Say I have an array @a_array which contain objects which are in turn arrays with 6 elements. I am trying to delete objects from that array whose first element equals an element of another array.

So far I have got this far (assume that @a_array and @ignore_variables has been declared and populated earlier).

my $i;
my $j;
for $i (0 .. $#a_array) {
$j=0;
for $j (0 .. $#ignore_variables){

if ($ignore_variables[$j] eq $a_array[$i][0]) {

# Remove it from the array.
delete @a_array[$i];
}
}
}

However, this does not work properly. It removes the values of the object at [$i] but it does not actually remove the object as the array remains the same length and when printed out has a gap where the variable that was deleted was.

What am I doing wrong!

Cheers

Rob

 

[justice41]

It is dangerous to change the size of an array that you are looping over. You would use [tt]splice()[/tt] rather than [tt]delete[/tt] to remove the element of an array, but in this case that won't work properly because you are looping over the array that you are changing. This does screwy things.

You would be better off to create a new array and only copy elements over from @a_array that don't match your ignore list. At the end of the loop you can copy the new array back to @a_array if you wish.

jaa

 

[toolkit]

One way to do this:

@bad = qw( 0 2 4 6 8 10 );

@test = qw( 0 1 2 3 4 5 6 7 8 9 10 );

# hash slice
@bad_hash{@bad} = @bad;

@ok = grep { !exists $bad_hash{$_} } @test;

print "\@ok: @ok\n";

Cheers, Neil

 

[justice41]

A slight modification of Neil's idea would work for your multidimentional array, @a_array.
(untested)

@ok =  grep { !exists $bad_hash{$_->[0]} } @test;

You could even replace @ok with @test and do a direct replacement.

jaa

 

[milage]

Cheers,

thanks for the suggestions. I went for the copying the ones I wanted to keep into a temporary array and then copying this back onto @a_array approach in the end.

Rob