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RE: How Do You Reduce Multiple Elements in a List?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33883] RE: [mg33863] How Do You Reduce Multiple Elements in a List?
  • From: "DrBob" <majort at cox-internet.com>
  • Date: Sun, 21 Apr 2002 06:12:36 -0400 (EDT)
  • Reply-to: <drbob at bigfoot.com>
  • Sender: owner-wri-mathgroup at wolfram.com

Frequencies in the DataManipulation package will do that for you.

Bobby

-----Original Message-----
From: Bob Harris [mailto:nitlion at mindspring.com] 
To: mathgroup at smc.vnet.net
Subject: [mg33883] [mg33863] How Do You Reduce Multiple Elements in a List?

Howdy,

This seems like such a simple thing, yet I've search through the big
book
trying to figure it out.  Perhaps someone can help me...

Given a list of integers that generally contains the same number many
times,
I'd like to reduce it to a list that just gives me the number/count
pairs.
For example, I'd like to convert the list
   {1, 1, 1, 1, 1, 2, 2, 2, 4, 4, 4, 4, 4, 4}
into
   {{1,5}, {2,3}, (4,6}}

Is there a built-in function to do this?  Seems like a histogramming
operation, but I get no useful matches from ?*Hist*.

Thanks,
Bob H






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