Re: position of sequence of numbers in list
- To: mathgroup at smc.vnet.net
- Subject: [mg107009] Re: [mg106976] position of sequence of numbers in list
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Sun, 31 Jan 2010 05:58:47 -0500 (EST)
- References: <201001301212.HAA25132@smc.vnet.net>
- Reply-to: drmajorbob at yahoo.com
I had no idea this would work... but it does. list = {1, 2, 3, 4, 5}; Position[list, Sequence[3, 4]] {{3}} My first thought was list /. {before___, 3, 4, ___} :> 1 + Length@{before} 3 But the other is far simpler. Bobby On Sat, 30 Jan 2010 06:12:04 -0600, JB <jkerrb at gmail.com> wrote: > Hi, > > What is the most efficient way to find the position of the beginning > of a sequence of numbers from a list? > > I found a couple of ways: > > find 3,4 in list={1,2,3,4,5}; > > 1. pos=Intersection[Position[list,3],(Position[list,4])+1] > > 2. pos=Position[Partition[list,2,1],{3,4}] > > Are there other ways to do this? > What is the best way when dealing with large lists? > > Thanks, > JB > -- DrMajorBob at yahoo.com
- References:
- position of sequence of numbers in list
- From: JB <jkerrb@gmail.com>
- position of sequence of numbers in list