Re: Unsorted Union

*To*: mathgroup at smc.vnet.net*Subject*: [mg61494] Re: Unsorted Union*From*: Konstantin L Kouptsov <klk206 at panix.com>*Date*: Wed, 19 Oct 2005 23:08:14 -0400 (EDT)*References*: <dj4p6t$gpt$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Robert Schoefbeck wrote: > 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 > Actually, it soes not: In[2]:= UnsortedUnion[{a, b, c, c, c, c, b}] Out[2]:= {a,b,c}