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MathGroup Archive 2005

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Re: Count using pattern on two different matrices

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57082] Re: [mg57079] Count using pattern on two different matrices
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 15 May 2005 03:03:35 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

L1=Table[Random[Integer]==1,{5},{2}]

{{True, False}, {True, True}, {True, False}, {True, True}, 
  {True, False}}

L2=Table[Random[Integer]==1,{5},{3}]

{{False, True, True}, {True, True, True}, 
  {False, True, True}, {False, True, True}, 
  {False, True, False}}

Count[Thread[{L1[[All,2]],L2[[All,3]]}],
  _?(#[[1]]==False&&#[[2]]==True&)]

2

Count[Thread[{L1[[All,2]],L2[[All,3]]}],
  _?(Not[#[[1]]]&&#[[2]]&)]

2


Bob Hanlon

> 
> From: Lee Newman <leenewm at umich.edu>
To: mathgroup at smc.vnet.net
> Date: 2005/05/14 Sat AM 04:58:25 EDT
> Subject: [mg57082] [mg57079] Count using pattern on two different matrices
> 
> 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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