Re: Classifying by Inequalities???

• To: mathgroup at smc.vnet.net
• Subject: [mg29258] Re: Classifying by Inequalities???
• From: "Orestis Vantzos" <atelesforos at hotmail.com>
• Date: Fri, 8 Jun 2001 04:15:42 -0400 (EDT)
• Organization: National Technical University of Athens, Greece
• References: <9fk3i8\$t4j\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```A slightly more elegant solution:
labelF[{A_,B_}]/;(A<0&&B<0&&A!=B) := k;
labelF[{A_,B_}]/;(A<0&&B=0) := l;
...
labelF[{A_,B_}]/;(A>0&&B>0&&A!=B) := p;
...
Notice that using an explicit inequality in the definitions of k and p,

Then you just Map labelF to your list:
labelF /@ myList
Orestis Vantzos

<BobHanlon at aol.com> wrote in message news:9fk3i8\$t4j\$1 at smc.vnet.net...
>
> In a message dated 2001/6/4 5:52:09 AM, Moranresearch at aol.com writes:
>
> >I have a series of integers l1={{a1,b1},{a2,b2},...{ai,bi}}
> >I want to label each pair in the series according to the inequality rules
> >
> >defined below
> >such that I get a series of labels l2={n,k,p....}
> >
> >k   =  A<0  B<0
> >l   =  A<0  B=0
> >m   =  A<0  B<0 A=B
> >n   =  A<0  B>0
> >p   =  A>0  B>0
> >q   =  A=0  B>0
> >r   =  A>0  B>0 A=B
> >
>
> You cannot test with your rules in the order given. For example, any pair
> meeting the condition for m, that is, A<0 && B<0 && A==B (which is
> more simply A<0 && A==B) would always first meet the condition for k.
> Likewise, the condition for r would always be met first by the condition
> for p.
>
> Generate random data restricted to meet one of your conditions (that is,
> there are pairs which do not meet any of your conditions such as
> {0, 0}, {0, -1}, {1, 0}, {1, -1})
>
> l1 = Select[
>       Table[{Random[Integer, {-2, 2}],
>           Random[Integer, {-2, 2}]}, {50}], #[[1]]<
>               0&&#[[2]]==#[[1]]||
>           #[[1]]<0&&#[[2]]<
>               0||
>           #[[1]]<0&&#[[2]]\[Equal]0||
>           #[[1]]<
>               0&&#[[2]]>0||
>           #[[1]]==0&&#[[2]]>0||
>           #[[1]]>
>               0&&#[[2]]==#[[1]]||
>           #[[1]]>0&&#[[2]]>0&];
>
> You can use a Which statement
>
> ans = (Which[
>           #[[1]]<0 && #[[2]]==#[[1]],m,
>           #[[1]]<0 && #[[2]]<0,k,
>           #[[1]]<0 && #[[2]]==0,l,
>           #[[1]]<0 && #[[2]]>0,n,
>           #[[1]]==0 && #[[2]]>0,q,
>           #[[1]]>0 && #[[2]]==#[[1]],r,
>           #[[1]]>0 && #[[2]]>0,p]&/@l1)
>
> {n, n, k, n, n, k, l, k, n, q, n, p, r,
>   k, l, n, m, n, r, n, n, r, k, n, m,
>   n, n, k, l, n, q, m, r, p, l}
>
> or you can nest several If statements
>
> ans = (If[#[[1]]<0,
>           If[#[[2]]==#[[1]],m,
>             If[#[[2]]<0,k,
>               If[#[[2]]==0,l,n]]],
>           If[#[[1]]==0&&#[[2]]>0,q,
>             If[#[[1]]>0,
>               If[#[[2]]==#[[1]],r,
>                 If[#[[2]]>0,p]]]]]&/@l1)
>
> True
>
>
> Bob Hanlon
> Chantilly, VA  USA
>

```

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