Re: Pattern Matching Problem
- To: mathgroup at smc.vnet.net
- Subject: [mg43389] Re: Pattern Matching Problem
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Fri, 29 Aug 2003 07:15:49 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <bihp1v$b3u$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
you mean
Plus @@@ Split[List @@ expr, Head[#1] === Head[#2] &]
or
{Select[#, Symbol === Head[#] &], Select[#, f === Head[#] &]} & [expr]
or
Plus @@@ {Cases[#, _Symbol], Cases[#, _f]} & [expr]
or
(lst = Cases[#, _.*_f]; {# - Plus @@ lst, Plus @@ lst}) & [expr]
or
{DeleteCases[#, _.*_f], Cases[#, _.*_f]} &[expr]
?
Regards
Jens
"Ersek, Ted R" wrote:
>
> Consider the following:
>
> In[1]:=
> ClearAll[f,a,b,c,w,x,y,z];
> expr=a+b+c+f[w,2]+f[w,3]+x+f[x,2]+f[x,3]+y+f[y,2]+f[z,2];
>
>
> Can somebody suggest a general way to seperate the terms above into like
> groups. By "like" I mean having the same second argument for (f). So for
> this example I want to get
>
> {a+b+c+x+y, f[w,2]+f[x,2]+f[y,2]+f[z,2], f[w,3]+f[x,3]}
>
> The pattern matcher should be able to do this because Plus has attributes
> Flat and Orderless. However I can't find a way to make it happen.
>
> -------------------
> Thanks,
> Ted Ersek