Re: Partitioning a list from an index

*To*: mathgroup at smc.vnet.net*Subject*: [mg56953] Re: Partitioning a list from an index*From*: bghiggins at ucdavis.edu*Date*: Wed, 11 May 2005 05:24:08 -0400 (EDT)*References*: <d5mv78$e05$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Guy, Here is one way to do the task: partitionfunc[start_, size_, alist_] := alist /. {x1___, x_ /; x == start, y___} :> {x1, Apply[ Sequence, Partition[Flatten[{x, Drop[{y}, -Mod[Length[{x, y}], size]]}], size]], Apply[Sequence, Take[{y}, -Mod[Length[{x, y}], size]]]} In[57]:=partitionfunc[4,2,list1] Out[57]={1,2,3,{4,5},{6,7},{8,9},10} I am sure others will have a less kludgy way to do it. Cheers, Brian Guy Israeli wrote: > hello, > > how can partition a list (doesn't have to be with 'Partition') such that the > partition will begin with a specific index? > > like this: > > list1={1,2,3,4,5,6,7,8,9,10} > > and i might want to split it to pairs or threes from index 6 for example, so > for threes it will be > > {1,2,{3,4,5},{6,7,8},9,10} > > with or without padding to those that are left, depends on what it is > possible, or maybe put them together or something > > for pairs it will be {1,{2,3},{4,5},{6,7},{8,9},10} > again with or without padding > > thank you very much > > Guy