Q: Union and SameTest Option

• To: mathgroup at smc.vnet.net
• Subject: [mg16016] Q: Union and SameTest Option
• From: Clemens Frey <btml01 at uni-bayreuth.de>
• Date: Sat, 20 Feb 1999 02:52:06 -0500
• Sender: owner-wri-mathgroup at wolfram.com

```Hi Mathematica-Groupers!

Can anybody explain to me what's going on here ?

In[270]:=
Union[ {{a,b,1},{a,c,1},{x,y,2},{a,b,2}},
SameTest->(#1[[2]]===#2[[2]]&) ]
Out[270]=
{{a,b,1},{a,c,1},{x,y,2}}

is ok since the first and the last list element have the same second
component. But what is wrong here now ?

In[272]:=
Union[ {{a,b,1},{a,c,1},{x,y,2},{a,b,2}},
SameTest->(#1[[3]]===#2[[3]]&) ]
Out[272]=
{{a,b,1},{a,b,2},{a,c,1},{x,y,2}}

Clemens

------------------------------------------------------------
Clemens Frey
Doctoral Student at the
Department of Mathematics/BITOEK
University of Bayreuth(Germany)

clemens.frey at uni-bayreuth.de
http://www.bitoek.uni-bayreuth.de/~Clemens.Frey
------------------------------------------------------------

```

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