Re: Need a functional process for this.

• To: mathgroup at smc.vnet.net
• Subject: [mg55610] Re: [mg55589] Need a functional process for this.
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 31 Mar 2005 01:24:02 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

```aa={2,5,7,9,11};

bb={{6,4},{9,2},{5,6},{3,8}};

Select[bb, !MemberQ[aa,#[[1]]]&&
!MemberQ[aa,#[[2]]]&]

{{6, 4}, {3, 8}}

This can be simplified with a helper function

anyMemberQ[lst_List, forms_List] :=
Or@@(MemberQ[lst,#]&/@forms);

Select[bb, !anyMemberQ[aa,#]&]

{{6, 4}, {3, 8}}

To handle the situation when aa may be either a list of lists or either a vector
or a list of lists, use Flatten

aa={{2}, {5}, {7}, {9}, {11}};

Select[bb, !MemberQ[Flatten[aa],#[[1]]]&&
!MemberQ[Flatten[aa],#[[2]]]&]

{{6, 4}, {3, 8}}

Select[bb, !anyMemberQ[Flatten[aa],#]&]

{{6, 4}, {3, 8}}

Bob Hanlon

>
> From: Steve Gray <stevebg at adelphia.net>
To: mathgroup at smc.vnet.net
> Date: 2005/03/30 Wed AM 03:22:03 EST
> To: mathgroup at smc.vnet.net
> Subject: [mg55610] [mg55589] Need a functional process for this.
>
> 	I have two lists, aa and bb. aa has the general form {2,5,7,9,11,...}
> (or{{2},{5},{7},{9},{11},?}}), and bb has the general form
{{6,4},{9,2},{5,6},{3,8},?}. If either
> the first or second element in any sublist (pair of integers) of bb matches
any element in aa, I
> want to delete that sublist from bb. In the above example, neither member
of {6,4} or {3,8} belongs
> to aa, while at least one element of {9,2} and {5,6} belongs to aa, so bb
becomes {{6,4},{3,8}}. If
> aa had only one element, for example 7, I could do
bb=Delete[bb,Position[bb,{x_,7}|{7,y_}]], but I
> don't know how to do it for several values instead of just "7" without using
a procedural loop.
> 	What is a good functional way to do this?
> 	Thank you for any tips.
>
> Steve Gray
>
>

```

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