Re: pattern matching and droping elements from list of lists.

• To: mathgroup at smc.vnet.net
• Subject: [mg49775] Re: pattern matching and droping elements from list of lists.
• From: "Dr. Wolfgang Hintze" <weh at snafu.de>
• Date: Fri, 30 Jul 2004 06:02:27 -0400 (EDT)
• References: <ceargm\$av9\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Define

In[34]:=
li = Outer[List, {a, b, c}, {a, b, c}, {a, b, c}];

Optional simplification of the list

In[36]:=
x = Flatten[li, 2];

Operation yielding what you wanted

In[37]:=
Complement[x, Select[x, Equal @@ #1 & ]]

Out[37]=
{{a, a, b}, {a, a, c}, {a, b, a}, {a, b, b}, {a, b, c},
{a, c, a}, {a, c, b}, {a, c, c}, {b, a, a}, {b, a, b},
{b, a, c}, {b, b, a}, {b, b, c}, {b, c, a}, {b, c, b},
{b, c, c}, {c, a, a}, {c, a, b}, {c, a, c}, {c, b, a},
{c, b, b}, {c, b, c}, {c, c, a}, {c, c, b}}

Checkinh lengths

In[4]:=
Length[x]
Length[y]

Out[4]=
27

Out[5]=
24

Regards,
Wolfgang

sean kim wrote:

> hello group,
>
> Outer[List, {a, b, c}, {a, b, c}, {a, b, c}]
>
> will output
>
> {{
> {{a, a, a}, {a, a, b}, {a, a, c}}, {{a, b, a}, {a, b, b}, {a, b, c}},
> {{a, c, a}, {a, c, b}, {a, c, c}}},
> {{{b, a, a}, {b, a, b}, {b, a, c}}, {{b, b, a}, {b, b, b}, {b, b, c}},
> {{b, c, a}, {b, c, b}, {b, c, c}}},
> {{{c, a, a}, {c, a, b}, {c, a, c}}, {{c, b, a}, {c, b, b}, {c, b, c}},
> {{c, c, a}, {c, c, b}, {c, c, c}}
> }}
>
> how do I remove {a,a,a} and {b,b,b} and {c,c,c} from above?
>
> thanks all in advance for any insights
>
> sean
>
>

```

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