Re: Re: Subsets
- To: mathgroup at smc.vnet.net
- Subject: [mg5028] Re: Re: [mg4962] Subsets
- From: Allan Hayes <hay at haystack>
- Date: Sat, 19 Oct 1996 16:40:32 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Eugene Lee has enquired about the extra entries used in Thread in =
the code mySubs2.
These are in case the list has some lists as members - they cause =
the threading to be over the first entry only. Here are two =
examples - I omit the error messages.
mySubs2[lis_List]:=3D
Fold[ Join[#1, Thread[Unevaluated[Append[#1,#2]], List,1]]&, =
{{}}, lis]
mySubs3[lis_List]:=3D
Fold[Join[#1, Thread[Unevaluated[Append[#1,#2]]]]&, {{}}, =
lis]
lis1 =3D {{1,2},{3,4}};
lis2 =3D {{1,2},{3,4,5}};
mySubs3[lis1]
mySubs3[lis1]
mySubs2[lis1]
mySubs2[lis2]
Allan Hayes
hay at haystack.demon.co.uk
http://www.haystack.demon.co.uk