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Re: Replace, test question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg120327] Re: Replace, test question
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Tue, 19 Jul 2011 06:55:43 -0400 (EDT)
  • Reply-to: hanlonr at cox.net

data /. _?PrimeQ -> P

data /. x_ /; PrimeQ[x] -> P


Bob Hanlon

---- PA32R <tio540s1 at gmail.com> wrote: 

=============
I'm very new to Mathematica and trying to work my way through it. I
don't understand why:
{58, 61, 15, 66, 10, 2, 24, 81, 45, 84} /. x_ /; PrimeQ -> P
returns:
{58, 61, 15, 66, 10, 2, 24, 81, 45, 84}

I would expect it to take the list, replace everything in the list
that matches any pattern and passes the PrimeQ test, i.e., is prime,
with P to yield:
{58, P, 15, 66, 10, P, 14, 81, 45, 84}

Can someone explain my misunderstanding?

Thanks.


--

Bob Hanlon



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