Re: newbie list question

*To*: mathgroup at smc.vnet.net*Subject*: [mg115023] Re: newbie list question*From*: image_doctor <matthew.prior at gmail.com>*Date*: Tue, 28 Dec 2010 06:52:48 -0500 (EST)*References*: <if70bt$330$1@smc.vnet.net>

On Dec 26, 9:02 am, Gareth Edwards <gareth.edwa... at cubicmotion.com> wrote: > Hi, > > Liking Mathematica a lot, but struggling with the early part of the learning curve, i.e. don't know what I don't know... > > What would be the neatest syntax for finding the first location of elements from one list in another? For example: > > listA = { 4,5,8,2,6,4 } > listB = { 8,4,2 } > > I would like a function to return {3,1,4} in this case (the first location in A of each element in B) > > Many thanks! You could try this .... F[A_, B_] := Flatten@(First /@ (Position[A, #] & /@ B /. {} -> 0))