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Re: position of sequence of numbers in list

  • To: mathgroup at smc.vnet.net
  • Subject: [mg107005] Re: [mg106976] position of sequence of numbers in list
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 31 Jan 2010 05:58:00 -0500 (EST)
  • Reply-to: hanlonr at cox.net

Position[list, Sequence[3, 4]]


Bob Hanlon

---- 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



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