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.
>

(Join @@ Position[a[[#1]], 1] & ) /@
Level[Position[a, _List], {-1}]

{{1, 3, 5, 6}, {3, 4, 6}}
???

Torsten

```

• Prev by Date: Re: how to make conditional summation
• Next by Date: Re: work with graphics and output in a different notebook from the one containing your code
• Previous by thread: Re: Position function
• Next by thread: Re: Position function