Re: Replace, test question

*To*: mathgroup at smc.vnet.net*Subject*: [mg120335] Re: Replace, test question*From*: DrMajorBob <btreat1 at austin.rr.com>*Date*: Tue, 19 Jul 2011 06:57:09 -0400 (EDT)*References*: <201107181013.GAA26882@smc.vnet.net>*Reply-to*: drmajorbob at yahoo.com

{58, 61, 15, 66, 10, 2, 24, 81, 45, 84} /. x_ /; PrimeQ@x -> P {58, P, 15, 66, 10, P, 24, 81, 45, 84} or {58, 61, 15, 66, 10, 2, 24, 81, 45, 84} /. x_?PrimeQ -> P {58, P, 15, 66, 10, P, 24, 81, 45, 84} Bobby On Mon, 18 Jul 2011 05:13:23 -0500, 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. > -- DrMajorBob at yahoo.com

**References**:**Replace, test question***From:*PA32R <tio540s1@gmail.com>