Re: "In progress" saving of data collected using Reap/Sow

*To*: mathgroup at smc.vnet.net*Subject*: [mg66217] Re: "In progress" saving of data collected using Reap/Sow*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Thu, 4 May 2006 05:20:58 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

On 5/3/06 at 2:44 AM, koopman at sfu.ca (Ray Koopman) wrote: >Expanding on my previous post, here are three ways to unravel z into >a simple list of all the past results. The first way is fastest, but >doesn't work if each result itself is a list. You had suggested two methods for dealing with things when the result is a list, i.e., > Nest[FlattenAt[#,1]&,z,n] === y > Table[Last@Nest[First,z,n-i],{i,n}] === y If the result is a list with known constant length then it is much faster to do Partition[Flatten@z, len] where len is the known constant len. For example, In[27]:= n = 10^3; z = {}; Timing[Do[z = {z, {i, -i}}, {i, n}]; ] Timing[a=Nest[FlattenAt[#1, 1] & , z, n]; ] Timing[Table[Last[Nest[First, z, n - i]], {i, n}]; ] Timing[b=Partition[Flatten[z], 2]; ] a==b Out[28]= {0.003924 Second,Null} Out[29]= {0.062477 Second,Null} Out[30]= {0.387071 Second,Null} Out[31]= {0.001232 Second,Null} Out[32]= True -- To reply via email subtract one hundred and four