Re: Insulating data from code

*To*: mathgroup at smc.vnet.net*Subject*: [mg66567] Re: Insulating data from code*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Sat, 20 May 2006 04:47:28 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 5/17/06 at 3:29 AM, koopman at sfu.ca (Ray Koopman) wrote: >>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? Here is an alternative that has no explicit pointer and avoids the issue you mention copyPartition[A_List, B_List] := ((Take[A, #]) & /@ Transpose@{Most@#, Rest@# - 1}) &[FoldList[Plus, 1, Length /@ B]] -- To reply via email subtract one hundred and four