Re: ReplaceAll applied to List
- To: mathgroup at smc.vnet.net
- Subject: [mg72335] Re: ReplaceAll applied to List
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Tue, 26 Dec 2006 06:38:49 -0500 (EST)
- Organization: The Open University, Milton Keynes, UK
- References: <em8jdu$pel$1@smc.vnet.net>
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}
<snip>
You could use the built-in function *Replace* [1] with its third
argument set to one (that is only the first level of the list will be
analyzed):
"Replace[expr, rules, levelspec] applies rules to parts of expr
specified by levelspec."
For instance,
In[1]:=
Replace[{1., {2}, 3}, (x_)?NumericQ :> g, 1]
Out[1]=
{g, {2}, g}
Regards,
Jean-Marc
1. http://documents.wolfram.com/mathematica/functions/Replace