Re: Re: Re: problem with Pick

*To*: mathgroup at smc.vnet.net*Subject*: [mg78354] Re: [mg78319] Re: [mg78209] Re: [mg78194] problem with Pick*From*: János <janos.lobb at yale.edu>*Date*: Fri, 29 Jun 2007 05:40:02 -0400 (EDT)*References*: <acbec1a40706230431p4f1db9a9i4320680dda027396@mail.gmail.com> <200706251106.HAA05048@smc.vnet.net> <6321860.1182850677359.JavaMail.root@m35> <200706280826.EAA20408@smc.vnet.net>

Like barbers who are shaving themselves... :) J=E1nos P.S. I am hearing someone turning slowly in his grave.... On Jun 28, 2007, at 4:26 AM, DrMajorBob wrote: > That's entirely contrary to the documentation, which says that Pick > "picks > out those ELEMENTS of list for which the corresponding ELEMENT of > sel is > True." > > How is a list its own ELEMENT, if English words mean anything? > > Bobby > > On Tue, 26 Jun 2007 03:08:14 -0500, Oyvind Tafjord > <tafjord at wolfram.com> > wrote: > >> Chris Chiasson wrote: >>> Step to reproduce: >>> 1. Evaluate these two inputs with a fresh kernel: >>> Pick[{a,b},z[{},{1}],{__}] >>> Pick[{a,b},{{},{1}},{__}] >>> >>> Expected results: >>> {b} >>> {b} >>> >>> Actual results: >>> {b} >>> {a,b} >>> >>> Relevant Documentation: >>> Pick[list,sel,patt] picks out those list[[i1,i2,...]] for which >>> sel[[i1,i2,...]] matches patt. >> >> In this case, sel={{},{1}}. sel[[]] matches patt, and so list[[]] is >> picked out. >> >> This behavior, in which all of list gets picked, does produce a fair >> amount >> of confusion, unfortunately. It often shows up in connection with >> Except: >> >> In[1]:= Pick[{a, b, c}, {1, 2, 3}, Except[2]] >> Out[1]= {a, b, c} >> >> In[2]:= Pick[{a, b, c}, {1, 2, 3}, Except[2, _Integer]] >> Out[2]= {a, c} >> >> Oyvind Tafjord >> Wolfram Research >> >>> >>> Relevant Evaluation: >>> In[3]:= MatchQ[{},{__}] >>> Out[3]= False >>> >>> In[4]:= {Internal`$CreationID,$Version} >>> Out[4]= {853857,6.0 for Microsoft Windows (32-bit) (April 27, >>> 2007) } >>> >>> -- >>> http://chris.chiasson.name/ >> >> >> > > > > -- > DrMajorBob at bigfoot.com

**References**:**problem with Pick***From:*"Chris Chiasson" <chris@chiasson.name>

**Re: Re: problem with Pick***From:*DrMajorBob <drmajorbob@bigfoot.com>