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Re: Position of element in a list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg16416] Re: Position of element in a list
  • From: Basudev Chaudhuri <bc26 at cornell.edu>
  • Date: Sat, 13 Mar 1999 02:21:35 -0500
  • Organization: Cornell University
  • References: <7bt665$ndn@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Roger,
The following works
Position[{-1, 3, -2, 1}, x_ /; x < 0 ]
Here you choose that patterns conditionally.
Hope this helps.
--Basu

Roger Mason wrote:

> Hi,
>
> I want to find the Position[] of negative elements in a list. The obvious
> methods do not work:
>
> Position[{-1, 3, -2, 1}, -_]
>
> and
>
> Position[{-1, 3, -2, 1}, -x_]
>
> return
>
> {}
>
> So how do I perform this apparently simple task?
>
> Thanks,
>
> Roger Mason



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