Re: List concatenation speed

*To*: mathgroup at smc.vnet.net*Subject*: [mg87589] Re: List concatenation speed*From*: "Szabolcs HorvÃt" <szhorvat at gmail.com>*Date*: Mon, 14 Apr 2008 05:41:01 -0400 (EDT)*References*: <4801C556.1060408@gmail.com>

On Sun, Apr 13, 2008 at 6:32 PM, Carlos Felippa <Carlos.Felippa at colorado.edu> wrote: > Hi, > > The problem with your solution is that the p's are not > available synchronously. They are Graphics objects, some quite > complicated, computed sequientally and catenated to form the Show[] > list. If I knew their number in advance I could use a Table > pre-reservation, say Table[0,{numberofobjects}], > to speed collocation. (I guess I could try that with > an overestimate and then do a Take) > Table[] generates the elements sequentially, so it might still be applicable to the problem. There are some other functions too, which collect partial results (NestList, FoldList, FixedPointList are a few examples). If it is not possible to express the algorithm with any of these functions, there is still a fast way to collect results: Sow[] and Reap[]. They are much faster than Append/AppendTo. Szabolcs