Re: Count using pattern on two different matrices

*To*: mathgroup at smc.vnet.net*Subject*: [mg57084] Re: [mg57079] Count using pattern on two different matrices*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Sun, 15 May 2005 03:03:38 -0400 (EDT)*References*: <200505140858.EAA09500@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

On 14 May 2005, at 17:58, Lee Newman wrote: > 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 > > Here is one way: l1 = {{True, False}, {False, True}, {False, False}} ; l2 = {{True, False, False}, {True, True, True}, {False, True, False}} ; Count[Transpose[{l1, l2}], _?(#1[[1,2]] == False && #1[[2,3]] == True & )] 0 Changing the criterion to L1[[row,2 ]]==False and L2[[row,3]]==False Count[Transpose[{l1, l2}], _?(#1[[1,2]] == False && #1[[2,3]] == False & )] 2 Andrzej Kozlowski

**References**:**Count using pattern on two different matrices***From:*Lee Newman <leenewm@umich.edu>