       Re: Count using pattern on two different matrices

• To: mathgroup at smc.vnet.net
• Subject: [mg57085] Re: [mg57079] Count using pattern on two different matrices
• From: DrBob <drbob at bigfoot.com>
• Date: Sun, 15 May 2005 03:03:38 -0400 (EDT)
• Organization: Deep Space Corps of Engineers
• References: <200505140858.EAA09500@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Length@Cases[Transpose@{L1, L2}, {{_, False}, {_, _, True}}]

Bobby

On Sat, 14 May 2005 04:58:25 -0400 (EDT), Lee Newman <leenewm at umich.edu> 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
>
>
>
>

--
DrBob at bigfoot.com

```

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