python-3.x - 如何将 Mathematica 中的代码转换为 Python？

Question

我使用以下 Mathematica 代码将图形的边长缩放为等于边权重。 ( ref )

edges = {1 <-> 2, 1 <-> 3, 1 <-> 4, 2 <-> 5, 2 <-> 6, 5 <-> 6, 
   3 <-> 4, 3 <-> 7, 6 <-> 7, 7 <-> 8, 2 <-> 9};

vd = {{75., 25., 0}, {115., 45., 0}, {10., 5., 0}, {45., 0, 0}, 
  {90., 60., 0}, {45., 55., 0}, {0, 25., 0}, {10., 50., 0}, {115.,  25.,0}};

vl = Range[Length@vd];

vcoords = MapIndexed[#2[[1]] -> # &, vd];
ew = {1 \[UndirectedEdge] 2 -> 49.6, 1 \[UndirectedEdge] 3 -> 74.4, 
 1 \[UndirectedEdge] 4 -> 49.6, 2 \[UndirectedEdge] 5 -> 37.2, 
 2 \[UndirectedEdge] 6 -> 74.4, 5 \[UndirectedEdge] 6 -> 49.6, 
 3 \[UndirectedEdge] 4 -> 37.2, 3 \[UndirectedEdge] 7 -> 24.8, 
 6 \[UndirectedEdge] 7 -> 62, 7 \[UndirectedEdge] 8 -> 37.2, 
 2 \[UndirectedEdge] 9 -> 24.8}

g3d = Graph3D[vl, edges, VertexCoordinates -> vcoords, 
  EdgeWeight -> ew, VertexLabels -> Placed["Name", Center], 
  EdgeLabels -> {e_ :> Placed["EdgeWeight", Center]}, 
  VertexSize -> .3, VertexStyle -> Red]
vars3d = Array[Through[{x, y, z}@#] &, Length @ vd];

λ = 1/100.;

obj3d = Total[(Norm[vars3d[[First@#]] - vars3d[[Last@#]]] - # /. ew)^2 & /@ 
  EdgeList[g3d]] +  λ Total[Norm /@ (vars3d - vd)];

lbnd = 0;
ubnd = 500;

solution3d = Last@Minimize[{obj3d, And @@ Thread[lbnd <= Join @@ vars3d <= ubnd]}, 
    Join @@ vars3d];

edgeLengths3d = # -> Norm[vars3d[[First@#]] - vars3d[[Last@#]]] /. 
     solution3d & /@ EdgeList[g3d];

Grid[Prepend[{#, # /. ew, # /. edgeLengths3d} & /@ 
   EdgeList[g3d], {"edge", "EdgeWeight", "Edge Length"}], 
 Dividers -> All]

我正在尝试用 Python 重写相同的代码。输入已转换为 python 数据类型列表和字典。

edges = [(1,2), (1,3), (1,4), (2,5), (2,6), (5,6), (3,4), (3,7), (6,7), (7,8), (2,9)];
vl = [1,2,3,4,5,6,7,8,9]
ew = {(1, 2) : 49.6, (1,3): 74.4, (1, 4) : 49.6, (2,5): 37.2, (2, 6) : 74.4, (5, 6): 49.6, 
     (3, 4) : 37.2, (3, 7):24.8, (6, 7) : 62, (7, 8) : 37.2, (2, 9) : 24.8}
vd = {1:[75., 25., 0], 2:[115., 45., 0], 3:[10., 5., 0], 4:[45., 0, 0], 
      5:[90., 60., 0], 6:[45., 55., 0], 7:[0, 25., 0], 8:[10., 50., 0], 9:[115.,  25.,0]}; 

我不确定必须如何在 Python 中转换优化命令。 关于如何在 Python 中编写行 obj3d 和 solution3d 的建议将有很大帮助。

Answer 1

How to convert code in Mathematica to Python?

如果代码很小(几百行)，最好手工转换(或转包)。

您需要阅读 Mathematica 的文档和 Python .

如果代码很大(几十万行)，你可以考虑编码 source to source译者。为此，请阅读 Dragon book然后选择一种高级编程语言(例如 Ocaml 或 SBCL 或 Haskell )来编写这样的翻译器(使用解析器生成器工具，如 Menhir 、 ANTLR 和受 Iburg 启发的方法等。 ..).预算半年的全职工作。