Re: Insulating data from code

*To*: mathgroup at smc.vnet.net*Subject*: [mg66591] Re: Insulating data from code*From*: Peter Pein <petsie at dordos.net>*Date*: Sun, 21 May 2006 00:29:41 -0400 (EDT)*References*: <e4ekai$9av$1@smc.vnet.net> <e4jtnn$d02$1@smc.vnet.net> <e4mn63$6o7$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Paul Abbott schrieb: > In article <e4jtnn$d02$1 at smc.vnet.net>, Peter Pein <petsie at dordos.net> > wrote: > >> Ray Koopman schrieb: >>> >From time to time I've wanted to partition the first level of one >>> list, say A, the same way that another list, say B, is partitioned. >>> One way to do this is >>> >>> copyPartition[A_List, B_List] /; Length@A >= Length@Flatten@B := >>> Module[{i = 0}, Map[A[[++i]]&,B,{-1}]] >>> >>> But all the methods I've thought of have a pointer that functions >>> something like i in the above code. I'd like to eliminate the pointer, >>> because in the unlikely event that A contains an unevaluated symbol >>> that is the same as the name of the pointer with $ appended -- e.g., >>> i$, if the pointer is i -- then in the returned list that symbol will >>> have a numeric value assigned to it. Unique[i] doesn't help. The >>> only solution I see is the probabilistic one of giving the pointer a >>> strange (random?) name that hopefully would be very unlikely to show >>> up as data. But that would be giving up. Does anyone have any ideas? >>> >> Hi Ray, >> >> use Replace[]: >> >> A={a,b,c,d,e}; >> B={{1},{2,3},{{{4}},5}}; >> >> Ap=B/.Thread[Flatten[B]\[Rule]A] >> --> {{a},{b,c},{{{d}},e}} > > No, that won't work. Try > > A={a,b,c,d,a}; > B={{1},{2,1},{{{3}},2}}; > > Ap=B/.Thread[Flatten[B] -> A] > > You get > > {{a}, {b, a}, {{{d}}, b}} > > whereas I think the OP wanted > > {{a}, {b, c}, {{{d}}, a}} > > Cheers, > Paul > > _______________________________________________________________________ > Paul Abbott Phone: 61 8 6488 2734 > School of Physics, M013 Fax: +61 8 6488 1014 > The University of Western Australia (CRICOS Provider No 00126G) > AUSTRALIA http://physics.uwa.edu.au/~paul > Hi Paul, well, I recognized this and came to a solution similar to J. Siehler's: A={a,{b,{c,{d,{e}}}},f}; B={x,{x},{{x,x},x},x}; cpStruct=ReplacePart[##, Sequence@@(Position[#,_,{-1},Heads->False]&/@{##})]&; cpStruct[B,A] --> {a,{b},{{c,d},e},f} Peter