Re: Changing the Natural Sort Order
- To: mathgroup at smc.vnet.net
- Subject: [mg49163] Re: Changing the Natural Sort Order
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Tue, 6 Jul 2004 03:33:21 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <ccb5hr$ekg$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
define your order
$myOrder = {a, d, b, c, f};
Symbols[expr_] := Union[Cases[expr, _Symbol, Infinity]]
orderQ[expr_] := Min[Flatten[Position[$myOrder, #] & /@ Symbols[expr]]]
In[]:=Sort[{h[x, g[a]], h[x, g[b]], h[x, g[c]], h[x, g[d]], h[x, g[f]]},
orderQ[#1] < orderQ[#2] &]
Out[]={h[x, g[a]], h[x, g[d]], h[x, g[b]], h[x, g[c]], h[x, g[f]]}
Regards
Jens
David Park wrote:
>
> Dear MathGroup,
>
> Is it possible to change the natural sort order of symbols that is used in Sort?
>
> I would like something like the following statement (that does not work).
>
> Assuming[d < b < c, Sort[{a, b, c, d, f}]]
>
> giving the desired output
>
> {a,d,b,c,f}
>
> I won't be sorting simple lists of symbols, but lists of similar, but unspecified, expressions that contain the symbols. For example...
>
> {h[x,g[a]], h[x,g[b]], h[x,g[c]], h[x,g[d]], h[x,g[f]]}
>
> which should give
>
> {h[x,g[a]], h[x,g[d]], h[x,g[b]], h[x,g[c]], h[x,g[f]]}
>
> Is there any way to do this?
>
> David Park
> djmp at earthlink.net
> http://home.earthlink.net/~djmp/