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MathGroup Archive 2005

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Count using pattern on two different matrices

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57079] Count using pattern on two different matrices
  • From: Lee Newman <leenewm at umich.edu>
  • Date: Sat, 14 May 2005 04:58:25 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

I have two matrices with an equal number of rows, but not necessarily 
columns, for example:

L1= {{True,False},{False, True},{False, False}, etc.....} ;
L2= {{True,False,False},{True, True,True},{False, True,False}, etc.....} ;

I would like to compute a count of the number of rows in which one of 
the columns of L1 meets some criterion, and one of the columns of L2 
meets some criterion, i.e.  If L1[[row,2 ]]==False  and 
L2[[row,3]]==True  then this row contributes 1 to the count.

I suspect that there is an elegant way to do this, perhaps using Count[] 
and MapThread, but I can't figure it out other than resorting to a 
rather clumsy For or Do loop that would check line by line and maintain 
a counter.

Any help would be appreciated,
Lee


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