Re: ReplaceAll applied to List
- To: mathgroup at smc.vnet.net
- Subject: [mg72331] Re: ReplaceAll applied to List
- From: dh <dh at metrohm.ch>
- Date: Tue, 26 Dec 2006 06:22:44 -0500 (EST)
- References: <em8jdu$pel$1@smc.vnet.net>
Hi Hannes,
parts of an expression also includes Heads. And a Head can be atomic or
not-a-list.
Daniel
Hannes Kessler wrote:
> Hello,
>
> I want to apply transformation rules to those elements of a list which
> are not lists themselves. The structure of the list is unknown in
> advance.
>
> The following simple examples illustrate my my problems with ReplaceAll
> and List:
>
> Expected result:
> {1., {2}, 3} /. x_?NumericQ :> g
> --> {g,{g},g}
>
> Unexpected result - inspite of AtomQ[{1., {2}, 3}] giving False
> {1., {2}, 3} /. x_?AtomQ :> g
> --> g[g, g[g], g]
>
> Similarly unexpected result - inspite of Not[ListQ[{1., {2}, 3}]]
> giving False
> {1., {2}, 3} /. x_?(Not[ListQ[#]] &) :> g
> --> g[g, g[g], g]
>
> Any explanations for this behavior?
>
> Thanks in advance,
> Hannes Kessler
>