Re: A Reap Sow question
- To: mathgroup at smc.vnet.net
- Subject: [mg65198] Re: A Reap Sow question
- From: dh <dh at metrohm.ch>
- Date: Fri, 17 Mar 2006 05:45:38 -0500 (EST)
- References: <dvdif7$a2p$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Hi Janos, there is something wrong with your questions. See below. Daniel János wrote: > Hi, > > First, thanks a lot to Valeri Astanoff, Daniel Lichtblau, David Park > and Carl Woll for the valuable suggestions to my previous post. > > Let say I have a construct like > > collection=Reap[i=1; While[i<=10,Sow[i]];] No real problem here, but you certainly want to increment i, otherwise you get an infinit loop. > > Is it possible to put a condition on Sow referring back to > collection ? Something like: > > collection=Reap[i=1; While[i<=10,If[Length[First[Last[collection]] ] > >5,,Sow[i] ] ];] Sure, but we have a real problem here. Before you execute your statement, collection has no value. Even during execution of the right side, collection has no yet a value. Therefore, what do you want to test? You could set collection to some value before execution of your statement. Your test would then apply to this value. Note also, if you execute the statement repeatetly, the test always concerns the previous value of collection. > > If not, - I have not seen any indication in Help either way - , what > technique can be used to get a similar effect without resorting to > global lists or arrays? > > Thanks ahead, > > János > > > ------------------------------------------------------ > I am seriously convinced that the world is ruled by complete > lunatics. The ones who are not crazy are either refraining from it, > or are unable to participate in it. <Leo Tolstoy> >