SortBy for multiple key sorts

*To*: mathgroup at smc.vnet.net*Subject*: [mg124026] SortBy for multiple key sorts*From*: Chris Young <cy56 at comcast.net>*Date*: Fri, 6 Jan 2012 04:16:01 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

Finally figured out a reasonably simple way to sort by two keys, in this case by the y-coordinates, and then within that sorting, by x-coordinates. This is just a standard way to sort points: from bottom to top in rows, and within each row from left to right. Why on earth can't Sort take a list of ordering functions so that the same thing can be done there? In[1200]:= pts = { {0, 2}, {1, 2}, {2, 2}, {4, 1}, {3, 1}, {6, 1}, {5, 1}, {7, 0}, {-1, 0} } In[1206]:= sortByYthenX = SortBy[pts, {Min[#[[2]]] &, Min[#[[1]]] &}] Out[1206]= {{-1, 0}, {7, 0}, {3, 1}, {4, 1}, {5, 1}, {6, 1}, {0, 2}, {1, 2}, {2, 2}}

**Follow-Ups**:**Re: SortBy for multiple key sorts***From:*Bob Hanlon <hanlonr357@gmail.com>