Re: Position function

*To*: mathgroup at smc.vnet.net*Subject*: [mg55573] Re: Position function*From*: Torsten Coym <torsten.coym at eas.iis.fraunhofer.de>*Date*: Wed, 30 Mar 2005 03:21:07 -0500 (EST)*References*: <d2b4q9$77c$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

konstantpi at mail15.com wrote: > suppose i have a List: > a={{1,3,1,2,1},{5,6,1,1,3,1}} > how i could know the positions of "1" in every sublist , i could use Position[a > [[1]],1] and Position[a[[2]],1] > but i want a one formula to give me {{1,3,5},{3,4,6}} > > the second question: > using Position[a,1] will give: > {{1, 1}, {1, 3}, {1, 5}, {2, 3}, {2, 4}, {2, 6}} > in general how to extract only the second item from every sublist so the output > will be; > {1,3,5,3,4,6} > thanks > konst. > What about: (Join @@ Position[a[[#1]], 1] & ) /@ Level[Position[a, _List], {-1}] {{1, 3, 5, 6}, {3, 4, 6}} ??? Torsten