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Re: Computing n-grams

  • To: mathgroup at smc.vnet.net
  • Subject: [mg88960] Re: [mg88913] Computing n-grams
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Thu, 22 May 2008 02:37:41 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

Use Partition

x = {a, b, c, d, e, f, g};

Partition[x, 2, 1]

{{a, b}, {b, c}, {c, d}, {d, e}, 
   {e, f}, {f, g}}

Partition[x, 3, 1]

{{a, b, c}, {b, c, d}, {c, d, e}, 
   {d, e, f}, {e, f, g}}


Bob Hanlon

---- "Coleman wrote: 
> Greetings,
> 
> Imagine one has a list such as {a,b,c,d,e,f,g}. I'm trying to find an
> efficient way in Mathematica to compute the n-grams of the list. That is, for
> n=2, the n-grams are all the lists of length 2 consisting of consecutive
> elements, e.g.,
> 
> {a,b},{b,c},{c,d},{d,e},...
> 
> While for n=3,
> 
> {a,b,c},{b,c,d},{c,d,e},..., and so on.
> 
> As I understand it, the built-in Mathematica commands such as Subsets or
> Permutations compute all possible list of size n, without regard to the
> order of the list elements.
> 
> Thanks,
> 
> Mark
> 
> 



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