[ktsirig]

Hi everybody!
I have a question concering arrays..
Say I have the following array:
(1,12)
(1,13)
(2,14)
(2,15)
(2,3)
(2,16)
(3,15)
(3,3)
(3,20)
(3,5)
(3,6)
(3,20)

Everything is OK except that pair (3,20) is repeated twice. How can I avoid it? 'Map' function is the answer?

[Amadeus]

Well, the Map function performs a user defined action on each element...I assume you are looking to eliminate the duplicate from the array. You'll likely have to traverse the array, and look for duplicates...is the array you have made up of elements encased in the parentheses, or is that several arrays you've specified?

Or if it is always the final element, you could use the pop function to remove it.

[Voodoo Doll]

Quote

Everything is OK except that pair (3,20) is repeated twice. How can I avoid it? 'Map' function is the answer?

Is an array the right data structure? If you don't want duplicates then maybe you were really looking for a hash instead of an array. As with everything in Perl, there are tons of ways to do what you want. I like this one though, because it's usually exactly what I want, and tells me that I probably should have been using a hash in the first place.

undef %hold;

# Initialize a hash with the array as keys
@hold{@my_array} = ();
# Grab the keys of the hash, sort if you want
# and assign them back to the array
@my_array = sort keys %hold;

[Amadeus]

Bam! Good call! I can't believe my mind didn't go straight to hash (no pun intended)

[ktsirig]

Thanx guys!
Great help!

PS: Amadeus, thanx also for your answer in my earlier post!
Very kind of you!

[ktsirig]

Oh, I'm stupid...

What I really have is an array of arrays that i want to make unique.
I give an example:
@AoA=(["1","15"], ["2","5"], ["3","4"], ["3","5"], ["3","8"], ["3","5"], ["4","6"], ["4","5"]);
and I want to remove array element ["3","5"] which is seen twice if you notice.
Is that possible? I am confused with this!

[Voodoo Doll]

It's possible, but it can get kind of ugly.

@AoA = grep !@hold{join '', @$_}++, @AoA;

Half the fun of Perl is figuring out how stuff like that works.

[Suman]

I have a problem in eliminating duplicates in array, i want the order of the eliments to be preserved but in hash you would not get the garantee that order is preserved. how do i over come this!!

[dcp]

In Python, you can define an iterator to return unique elements in order, then create the list...

>>> s = [(1, 12), (1, 13), (2, 14), (2, 15), (2, 3), (2, 16), (3, 15), (3, 3), (3, 20), (3, 5), (3, 6), (3, 20)]
>>> \
def iunique(iterable):
	"""From: http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/52560"""
	seen = set([])
	for i in iterable:
		if i not in seen:
			seen.add(i)
			yield i
>>> [ x for x in iunique(s) ]
[(1, 12), (1, 13), (2, 14), (2, 15), (2, 3), (2, 16), (3, 15), (3, 3), (3, 20), (3, 5), (3, 6)]
>>> 

Suman, on 5 May, 2006 - 07:11 AM, said:

I have a problem in eliminating duplicates in array, i want the order of the eliments to be preserved but in hash you would not get the garantee that order is preserved. how do i over come this!!