Using Select

*To*: mathgroup at smc.vnet.net*Subject*: [mg97371] Using Select*From*: "Karsten W." <Karsten.G.Weinert at googlemail.com>*Date*: Thu, 12 Mar 2009 02:16:40 -0500 (EST)

Hello, here is a problem I have solved but I am not happy with the method I have a data matrix DATA, a list of m ordered n-tuples. I run a function on the data matrix which returns a list DATAEVAL with m elements. The i-th element of this list corresponds to the i-th tuple of the data matrix. I think of this DATAEVAL list as an additional column of the data matrix. Now I am only interested in those tuples of the data matrix, where the corresponding DATAEVAL list has a value greater than zero. My current approach is the following: I add the DATAEVAL list to the data matrix and call Select afterwards: data = Import[...]; dataEval = f[data, ...]; filteredData = Select[Transpose[Join[Transpose[data], {dataEval}] ], Last[#] > 0 &]; This works. However, calling Transpose two times seems not to be the most efficient way to solve the problem. As a newbie to Mathematica (and functional programming), I wonder if you can point me to a simpler solution? Kind regards, Karsten.

**Follow-Ups**:**Re: Using Select***From:*DrMajorBob <btreat1@austin.rr.com>