Re: Count using pattern on two different matrices

*To*: mathgroup at smc.vnet.net*Subject*: [mg57088] Re: [mg57079] Count using pattern on two different matrices*From*: "David Park" <djmp at earthlink.net>*Date*: Sun, 15 May 2005 03:03:42 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Lee, First, generating a test case... genrandombool := If[Random[Integer, {0, 1}] == 0, False, True] L1 = Table[genrandombool, {3}, {2}] L2 = Table[genrandombool, {3}, {3}] {{True, False}, {False, True}, {True, False}} {{True, False, True}, {False, True, True}, {False, False, True}} Plus @@ MapThread[If[! Part[#1, 2] && Part[#2, 3], 1, 0] &, {L1, L2}] 2 David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Lee Newman [mailto:leenewm at umich.edu] To: mathgroup at smc.vnet.net 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