Re: conditionnal rule
- To: mathgroup at smc.vnet.net
- Subject: [mg51521] Re: [mg51499] conditionnal rule
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Thu, 21 Oct 2004 22:20:29 -0400 (EDT)
- Reply-to: hanlonr at cox.net
- Sender: owner-wri-mathgroup at wolfram.com
myList={{a,b},{c,d}};
myList/.{a_,x_?(!(Head[#]===List)&)}->{a,d}
{{a, d}, {c, d}}
myList/.{a_,x_?(Head[#]==Symbol&)}->{a,d}
{{a, d}, {c, d}}
myList/.{a_,x_?AtomQ}->{a,d}
{{a, d}, {c, d}}
myList/.{a_,x_?(Length[#]==0&)}->{a,d}
{{a, d}, {c, d}}
Bob Hanlon
>
> From: darkness_wizard at hotmail.com (Wishmaster7)
To: mathgroup at smc.vnet.net
> Date: 2004/10/20 Wed AM 01:21:19 EDT
> To: mathgroup at smc.vnet.net
> Subject: [mg51521] [mg51499] conditionnal rule
>
> hi all !!
>
> I want to apply a rule under a certain condition. here is the example :
>
> myList = {{a, b}, {c, d}};
>
> myList //. {a,x_}->{a,d}
>
> apply this rule if Length[x]===1 (this means that x can not be a list)
>
> I tried something like :
>
> myList //. {a_,x_}->{c,d}/;Length[x]===1
>
> or
>
> myList //. {a_,x_?Length[x]===1}->{c,d}/
>
> but it does not work.
>
> can someone help me ?
>
>