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MathGroup Archive 2005

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Extracting information from lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg63323] Extracting information from lists
  • From: "Tony King" <mathstutoring at ntlworld.com>
  • Date: Sat, 24 Dec 2005 07:18:50 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Does anyone know of a function that will allow me to extract the positions 
of the first elements of runs of similar elements within a list. For 
example, suppose that

list={7,9,1,6,8,1,1,6,5,1,1,1,8,7,6,1,1,1,1,7}

I need a function that will return

{3,6,10,16}

corresponding to the runs {1},{1,1},{1,1,1},{1,1,1,1} within list

Many thanks

Tony 


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