Re: selecting from lists

*To*: mathgroup at smc.vnet.net*Subject*: [mg6134] Re: [mg6120] selecting from lists*From*: Lou Talman <me at talmanl.mscd.edu>*Date*: Sun, 23 Feb 1997 00:10:47 -0500*Sender*: owner-wri-mathgroup at wolfram.com

Murray Eisenberg wrote: > The problem: given an arbitrary list v and a list b of the same > length, whose entries are all Boolean (True or False), construct a > function s[v, b] whose result is a list consisting only of those > entries of v for which the corresponding entries in b are True. For > example, > > v = {3, 82, 7, -12, 5}; > b = {False, True, True, False}; > s[v, b] > {82, 7} How about s[v_, b_] := Cases[Transpose[{v, b}], {x_, True} -> x] --Lou Talman