Re: Partition of multi dimension list

*To*: mathgroup at smc.vnet.net*Subject*: [mg52807] Re: Partition of multi dimension list*From*: "Ray Koopman" <koopman at sfu.ca>*Date*: Mon, 13 Dec 2004 04:23:40 -0500 (EST)*References*: <cpeje6$6sb$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Bruyndonckx P. wrote: > I have a list of about 5 million items. Each item is a list of > 7 integer numbers (hence a 5000000x7 array). I want to partition > this array on the values of two numbers in each item. The third > number (out of seven) goes from 0 to 63 and the fifth number is > either 0 or 1. So I want to end up with 64*2 partitions. The > fastest solution I have found up to now to do this on the list 'c' > is Flatten[CategoryLists[c, {_}, {_}, Range[64] - 1, {_}, {0,1}, > {_}, {_}][[1, 1]], 4]. Split[Sort[c, OrderedQ[{#1[[{3,5}]],#2[[{3,5}]]}]&], Equal[#1[[{3,5}]],#2[[{3,5}]]]&]