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RE: Map function which adds last two numbers of a list

• To: mathgroup at smc.vnet.net
• Subject: [mg73563] RE: [mg73530] Map function which adds last two numbers of a list
• From: "David Annetts" <davidannetts at aapt.net.au>
• Date: Thu, 22 Feb 2007 04:26:03 -0500 (EST)
• References: <200702210646.BAA18238@smc.vnet.net>

Hi Christopher,

>   Consider this:
> 
> z = {{1,4,5,6},{7,8,9,1},{1,2,4,3}}
> 
> I'd like to Map a function onto z which would replace the 
> last two items with their sum:
> 
> {{1,4,11},{7,8,10},{1,2,7}}
> 
> I could easily use the Table command to construct this new 
> table, but it would be nicer if I new how to Map some 
> function on z that would produce the same result.

You can use a rule for this:-

	zz = z /. {a_, b_, c_, d_} -> {a, b, c + d}

Regards,

Dave.

• References:
  • Map function which adds last two numbers of a list
    • From: "Christopher Pike" <crpike@ucdavis.edu>