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MathGroup Archive 2012

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Sorting coefficients

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124021] Sorting coefficients
  • From: Chris Young <cy56 at comcast.net>
  • Date: Fri, 6 Jan 2012 04:14:17 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

I'm trying to get my points sorted first by rows first. But I'm having
trouble figuring out how to do the kind of double sorting I need with
Sort. SortBy seems very hard to figure out and I'm not sure if it's
what I need here.

I've just got a hexagonal layout of point coordinates, with another one
on the origin, and I'm trying to sort everything from lower left to
upper right. I.e., the usual ordering of going through the bottom row
from left to right, then through the middle row from left to right, etc.

Any help appreciated.

Chris Young
cy56 at comcast.net


In[1043]:= Prepend[
 Table[{Re, Im}[ E^(k (2 \[Pi])/6 I)] // Through, {k, 0, 5}], {0, 0}]

Out[1043]= {{0, 0}, {1, 0}, {1/2, Sqrt[3]/2}, {-(1/2), Sqrt[3]/
  2}, {-1, 0}, {-(1/2), -(Sqrt[3]/2)}, {1/2, -(Sqrt[3]/2)}}

In[1046]:= Sort[%1043, #1[[2]] < #2[[2]] &]

Out[1046]= {{1/2, -(Sqrt[3]/2)}, {-(1/2), -(Sqrt[3]/2)}, {-1, 0}, {1,
  0}, {0, 0}, {-(1/2), Sqrt[3]/2}, {1/2, Sqrt[3]/2}}

In[1073]:= Sort[%1046, #1[[2]] < #2[[2]] &]

Out[1073]= {{-(1/2), -(Sqrt[3]/2)}, {1/2, -(Sqrt[3]/2)}, {0, 0}, {1,
  0}, {-1, 0}, {1/2, Sqrt[3]/2}, {-(1/2), Sqrt[3]/2}}




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