Re: Sorting question

*To*: mathgroup at smc.vnet.net*Subject*: [mg52791] Re: [mg52758] Sorting question*From*: DrBob <drbob at bigfoot.com>*Date*: Mon, 13 Dec 2004 04:22:55 -0500 (EST)*References*: <200412111023.FAA06589@smc.vnet.net>*Reply-to*: drbob at bigfoot.com*Sender*: owner-wri-mathgroup at wolfram.com

Maybe your data looked like {{1, 1}, {2, 3}, {3, 2}, {4, 4}}, rather than having all those parentheses? Anyway, here's a method that may work for you: data={{1,1},{2,3},{3,2},{4,4}} remover={a___,{d1_,t1_},{d2_,t2_},b___}/;t2<t1:>{a,b}; Sort@data/.remover {{1,1},{2,3},{3,2},{4,4}} {{1,1},{4,4}} data=RandomArray[ExponentialDistribution[0.1],{17,2}]; Sort@data %/.remover {{0.0384055,17.9033},{0.204296,6.29239},{0.575515,11.7231},{0.831196,3.07496},\ {1.5744,4.58849},{1.91661,8.39652},{2.25087,54.8277},{2.69083,6.83991},{2.\ 98937,10.3344},{4.80607,19.9063},{5.58785,0.687047},{8.57433,21.1495},{8.\ 75018,19.6064},{10.1908,7.97579},{10.9566,25.7916},{11.3327,8.29348},{25.78,8.\ 40211}} {{0.575515,11.7231},{0.831196,3.07496},{ 1.5744,4.58849},{1.91661,8.39652},{2.25087,54.8277},{ 2.69083,6.83991},{2.98937,10.3344},{4.80607,19.9063},{5.58785,0.687047},{ 8.57433,21.1495},{8.75018,19.6064},{10.1908,7.97579},{ 10.9566,25.7916},{11.3327,8.29348},{25.78,8.40211}} Bobby On Sat, 11 Dec 2004 05:23:38 -0500 (EST), Nimrod <jdedguard-agent at yahoo.co.uk> wrote: > A simple sorting question that has me stumped as to how to do it both > quickly and elegantly. > > I have a list of data pairs of the form (distance, time). I want to > sort on the distance element and then remove all pairs where the time > element is out of order with the distance element. For example > ((1,1),(2,3),(3,2),(4,4)) --> ((1,1),(4,4)). The actual lists are > much longer. > > Thanks in advnace, > > Nimrod. > > > > -- DrBob at bigfoot.com www.eclecticdreams.net

**References**:**Sorting question***From:*Nimrod <jdedguard-agent@yahoo.co.uk>