Re: how to apply Position repeatedly without a loop?
- To: mathgroup at smc.vnet.net
- Subject: [mg118652] Re: how to apply Position repeatedly without a loop?
- From: DrMajorBob <btreat1 at austin.rr.com>
- Date: Fri, 6 May 2011 07:22:01 -0400 (EDT)
a = {{1, 2, 3}, {3, 4, 5}, {6, 7, 8}}; elements = {3, 6}; Position[a, Alternatives @@ elements] {{1, 3}, {2, 1}, {3, 1}} Bobby On Thu, 05 May 2011 04:24:01 -0500, steveh44 <steve_h44 at yahoo.com> wrote: > i have matrix A and wanted to find the Positions in this matrix of > some elements which listed in some another vector. > > how to use Position to do it without a loop? > > I tried this: > > In[192]:= A={{1,2,3}, > {3,4,5}, > {6,7,8}}; > elements={3,6}; > > Position[A,r[[1]]] > Out[194]= {{1,1}} > > Position[A,r[[2]]] > Out[197]= {{1,2}} > > but I want to do something like > > Position[A,r] > but this does not work. > > I tried Map, Thread, etc.. but could not get it to work. not sure what > the syntax is. > > thanks for help > steve > > > -- DrMajorBob at yahoo.com