Re: Changing the Natural Sort Order

*To*: mathgroup at smc.vnet.net*Subject*: [mg50709] Re: [mg49144] Changing the Natural Sort Order*From*: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>*Date*: Fri, 17 Sep 2004 01:17:35 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

>-----Original Message----- >From: David Park [mailto:djmp at earthlink.net] To: mathgroup at smc.vnet.net >Sent: Monday, July 05, 2004 10:54 AM >To: mathgroup at smc.vnet.net >Subject: [mg50709] [mg49144] Changing the Natural Sort Order > > >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/ > > > > David, perhaps you can exploit this idea: In[9]:= Block[{c0, c1, c2, c3, c4}, Block[{a, b, c, d, f}, {a, b, c, d, f} = Hold /@ {c0, c2, c3, c1, c4}; Sort[{a, b, c, d, f}]] /. Thread[Hold /@ {c0, c2, c3, c1, c4} -> {a, b, c, d, f}]] Out[9]= {a, d, b, c, f} In[10]:= Block[{c0, c1, c2, c3, c4}, Block[{a, b, c, d, f}, {a, b, c, d, f} = Hold /@ {c0, c2, c3, c1, c4}; Sort[{h[x, g[a]], h[x, g[b]], h[x, g[c]], h[x, g[d]], h[x, g[f]]}]] /. Thread[Hold /@ {c0, c2, c3, c1, c4} -> {a, b, c, d, f}]] Out[10]= {h[x, g[a]], h[x, g[d]], h[x, g[b]], h[x, g[c]], h[x, g[f]]} I didn't do the work: generate & execute this code from the assumptions; and *all* Symbols occuring should be wrapped according to the new Ordering (including g,h,x, but that wasn't important in this very example). -- Hartmut