Re: Grouping {x,y z} data set

*To*: mathgroup at smc.vnet.net*Subject*: [mg99604] Re: [mg99583] Grouping {x,y z} data set*From*: Adriano Pascoletti <adriano.pascoletti at dimi.uniud.it>*Date*: Sat, 9 May 2009 03:19:53 -0400 (EDT)*References*: <200905080418.AAA16631@smc.vnet.net>

Consider this list of triples: t = {{68, 53, 2}, {57, 48, 5}, {3, 40, 4}, {56, 27, 3}, {2, 23, 3}, {2, 24, 1}, {34, 91, 2}, {14, 69, 5}, {25, 67, 0}, {43, 72, 2}}; 1. Solution using SortBy and SplitBy SplitBy[SortBy[t, Last], Last] gives {{{25, 67, 0}}, {{2, 24, 1}}, {{34, 91, 2}, {43, 72, 2}, {68, 53, 2}}, {{2, 23, 3}, {56, 27, 3}}, {{3, 40, 4}}, {{14, 69, 5}, {57, 48, 5}}} 2. Solution using Sow and Reap Reap[(Sow[Most[#1], Last[#1]] & ) /@ t, _, #1 -> #2 & ][[2]] gives {2 -> {{68, 53}, {34, 91}, {43, 72}}, 5 -> {{57, 48}, {14, 69}}, 4 -> {{3, 40}}, 3 -> {{56, 27}, {2, 23}}, 1 -> {{2, 24}}, 0 -> {{25, 67}}} Adriano Pascoletti 2009/5/8 graser <graser at gmail.com> > Hi! > > I have a question for you. > > I have arbitrary data set. > > For example, > > Data={{x_1,y_1,z_1},{x_2,y_2,z_1},{x_1, y_2, z_3},........{x_n, y_m, > z_L}} > > I tried to group this data set depending on z value. > > I mean I try to select all x, y values with same z value. > > But they are not evenly distributed and they are not integer either. > > please help me! > > Thanks! >

**References**:**Grouping {x,y z} data set***From:*graser <graser@gmail.com>