Re: style question
- To: mathgroup at smc.vnet.net
- Subject: [mg79332] Re: style question
- From: Peter Pein <petsie at dordos.net>
- Date: Wed, 25 Jul 2007 02:00:36 -0400 (EDT)
- References: <f84jp8$qmp$1@smc.vnet.net>
Yaroslav Bulatov schrieb:
> What is the recommended way of counting the number of matches in two
> lists?
>
> The natural way would be to thread over Equal, but Equal will evaluate
> before Thread gets to it. The method below works, but somehow feels
> wrong
>
> m1 = RandomInteger[{1}, {10^5, 2, 2}];
> m2 = RandomInteger[{1}, {10^5, 2, 2}];
> matches = Thread[temporary[m1, m2]] /. temporary -> Equal;
> Count[matches, True]
>
>
I would use
Count[Equal @@@ Transpose[{m1, m2}],True]
P^2