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5

I am not familiar with the specific output format you need but I think I can show you how to proceed. dat = Import["ExampleData/caffeine.xyz", {{"VertexTypes", "VertexCoordinates"}}]; dat2 = {#[[1, 1]], #[[All, 2]]} & /@ GatherBy[dat\[Transpose], First]; dat3 = {#, Length@#2, #2} & @@@ dat2; dat3 has this format: dat3 // TableForm $\left( ...


4

In version 10, you can use MeshCoordinates[ConvexHullMesh[...]] as in RunnyKine's answer, but you need to re-order them using MeshCells: pentagon=N@Table[{Cos[2 Pi k /5], Sin[2 Pi k /5]}, {k, 5}] points = N@RandomSample[Join[pentagon, {{0, 0}}]] chm=ConvexHullMesh[points]; ordering=MeshCells[chm,2][[1,1]] out=MeshCoordinates[chm][[ordering]] ...


3

If you have Version 10, you could use ConvexHullMesh. pts = RandomReal[{-10, 10}, {6, 2}]; You can then order them by doing: chull = ConvexHullMesh[pts]; And here are the points: MeshCoordinates[chull] Note: This does not always order the points but one can use MeshCells which will give the ordering correctly. See @kguler's answer.


2

Could use ConvexHull in the ComputationalGeometry standard add-on package. Needs["ComputationalGeometry`"] We'll create a simple example. pts = RandomReal[{-10, 10}, {6, 2}]; ListPlot[Append[pts, First[pts]], Joined -> True] Now find and plot the (ordered) outer points. hullindices = ConvexHull[pts]; hullpts = pts[[hullindices]]; ...


1

This is my attempt at producing the output style that you desire where i have assumed that all co-ordinates should be padded with three zeroes at the end. data = Import[ "ExampleData/caffeine.xyz", {{"VertexTypes", "VertexCoordinates"}}]; Gather co-ordinates of same elements table = Table[ If[data[[1, #]] == data[[1, i]], Sow[N[data[[2, i]]/100]], ...


1

The following works in your special case but can't be generalized. l = {"+", "m", "π", "[]", "2"}; SeedRandom@0; rl = RandomSample[l, 5]; g = With[{cg = CycleGraph[5]}, Graph[UndirectedEdge @@@ Thread@{rl, RotateLeft@rl}, VertexCoordinates -> (Rule @@@ Thread@{rl, VertexCoordinates /. AbsoluteOptions[cg, VertexCoordinates]}), ...



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