Unsorted Union
- To: mathgroup at smc.vnet.net
- Subject: [mg61434] Unsorted Union
- From: Robert Schoefbeck <schoefbeck at hep.itp.tuwien.ac.at>
- Date: Wed, 19 Oct 2005 02:16:12 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello all,
in the help section i found the following thing:
UnsortedUnion[x_] := Module[{f}, f[y_] := (f[y] = Sequence[]; y); f/@x]
It does just what it says:
UnsortedUnion[{a,c,b,d,a,b}]={a,c,b,d}
(ordinary Union would Sort the result)
my question is: How does the definition work? I know all the syntax
and i have been using these concepts for for some time now. But i cant
figure out what this definition does.
Robert