sharing/swapping items between lists

Ross ross.jett at
Tue Apr 14 19:34:07 CEST 2009

On Apr 14, 5:57 am, a... at (Aahz) wrote:
> In article <f64c9de2-3285-4f74-adb8-2111c78b7... at>,
> Ross  <ross.j... at> wrote:
> >On Apr 13, 9:08=A0am, a... at (Aahz) wrote:
> >> In article <c569228f-f391-4317-83a2-08621c601... at r8g2000yql.googlegroups.=
> >com>,
> >> Ross =A0<ross.j... at> wrote:
> >>>I'm example was probably a bad one. A better example of
> >>>output I would like would be something like [[1,2],[3,4],[5,6]] and
> >>>then for the leftovers list [7,8,9,10 etc]. What I'm trying to do is
> >>>produce some sort of round robin algorithm for tennis that is
> >>>constrained by the number of courts available each week. So if there
> >>>are only 3 courts available for a singles league and 10 people have
> >>>signed up, 4 players will have a bye each week. I want my algorithm to
> >>>produce unique matchups each week and also give each player the same
> >>>angle?
> >> How about Googling for "round robin algorithm python"? ;-)
> >I have the basic algorithm and it works fine...I'm just having trouble
> >adding another parameter to it that allows for court constraints and
> >bye weeks.
> You'll need to give us more information, then.  Why don't you start with
> the core algorithm you're using?
> --
> Aahz (a... at           <*>
> Why is this newsgroup different from all other newsgroups?

Here's the core algorithm I'm using:

>>> def round_robin(teams,rounds):
	if len(teams)%2:
	mid = len(teams) //2
	for i in range(rounds):
		yield zip(teams[:mid], teams[mid:])
		teams = teams[0:1] + teams[mid:mid+1] + teams[1:mid-1]+teams[mid

>>> if __name__== '__main__':
	rounds = 15
	teams = range(16)
	for round in round_robin(teams,rounds):
		print round

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