issue while evaluating MMA expression in Python

[DeepaMahm]

Hi All,
This is a follow up to the question posted here

I've the following MMA code

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]

Following the suggestions offered in the link shared above I installed wolframclient and tried the following

from wolframclient.evaluation import WolframLanguageSession
session = WolframLanguageSession()
from wolframclient.language import wlexpr


session.evaluate(wlexpr(
'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];'

'z1 = Values[solution3d] // Partition[#, 3] &;'

'theFile = File["op.txt"];'

'Export[theFile, z1, "Table"];'
    ))

but I get the following error

String expected at position 1 in StringForm[MessageName[General, msgl], $MessageList].
Undefined message MessageName[Message, msgl] with arguments {$MessageList}
The problem may be unbounded. Specifying a value for MaxIterations greater than 5000 may improve the solution.
String expected at position 1 in StringForm[MessageName[General, msgl], $MessageList].
Undefined message MessageName[Message, msgl] with arguments {$MessageList}
String expected at position 1 in StringForm[MessageName[General, msgl], $MessageList].
Further output of MessageName[StringForm, string] will be suppressed during this calculation.
The problem may be unbounded. Specifying a value for MaxIterations greater than 5000 may improve the solution.
String expected at position 1 in StringForm[MessageName[General, msgl], $MessageList].
Undefined message MessageName[Message, msgl] with arguments {$MessageList}
The problem may be unbounded. Specifying a value for MaxIterations greater than 5000 may improve the solution.
String expected at position 1 in StringForm[MessageName[General, msgl], $MessageList].
Undefined message MessageName[Message, msgl] with arguments {$MessageList}
String expected at position 1 in StringForm[MessageName[General, msgl], $MessageList].
Further output of MessageName[StringForm, string] will be suppressed during this calculation.
The problem may be unbounded. Specifying a value for MaxIterations greater than 5000 may improve the solution.

Suggestions on how to resolve this error will be really helpful.

[DbxDev]

This is the same WolframLanguage bug as witnessed in #22. It'll be fixed in 12.2 (I can reproduce on a 12.1 build, but not with a recent prototype build).
Messages that should be Quiet-ed, are incorrectly issued in some cases.

[DeepaMahm]

@DbxDev Thanks, could you please explain how to pass the input arguments from python to .m file and load it back as MMA expression in python {edges,vl,ew,vd}=ImportString[#,"PythonExpression"]&/@ {"[(1,2),(1,3),(1,4),(2,5),(2,6),(5,6),(3,4),(3,7),(6,7),(7,8),(2,9)]", "[1,2,3,4,5,6,7,8,9]","{(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}", "{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]}"}; ?

[DeepaMahm]

@DbxDev

I tried

   from wolframclient.evaluation import WolframLanguageSession
   from wolframclient.language import wl, wlexpr, Global

    session = WolframLanguageSession()

    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]}
    with WolframLanguageSession() as s:
        solution3d = wl.Get('test.m')
        s.evaluate(Global.solution3d(edges, vd, vl, ew))

test.m includes

solution3d[edges_, vd_, vl_, ew_] := (

    {edges,vl,ew,vd}=ImportString[#,"PythonExpression"]&/@{edges,vl,ew,vd};
    edges = UndirectedEdge @@@ edges; vcoords = List @@ vd;
    ew = Normal @ KeyMap[UndirectedEdge @@ # &,ew];

    g3d = Graph3D[vl, edges, VertexCoordinates -> vcoords, EdgeWeight->ew, VertexLabels->Placed["Name",Center],
    EdgeLabels->{e_:>Placed["EdgeWeight",Center]}, VertexSize->.5, BaseStyle->16];

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

    vars3d = Array[Through[{x, y, z}@#] &, Length@vd];
    \[Lambda] = 1/100.; lbnd = 0; ubnd = 500;

    obj3d = Total[(Norm[vars3d[[First@#]] - vars3d[[Last@#]]] - # /. (Rule @@@ ew))^2 & /@ EdgeList[g3d]] + \[Lambda] * Total[Norm /@ (vars3d - Values@vd)];
    solution3d = Last @ Minimize[{obj3d, And @@ Thread[lbnd <= Join @@ vars3d <= ubnd]}, Join @@ vars3d];

    edgeLengths3d = # -> Norm[vars3d[[First@#]] - vars3d[[Last@#]]] /.solution3d & /@ EdgeList[g3d];
    ResourceFunction["PrettyGrid"][{#, # /. ew, # /. edgeLengths3d} & /@EdgeList[g3d],  "ColumnHeadings" -> {"edge", "EdgeWeight", "Edge Length"}];

    z1 = Values[solution3d] // Partition[#, 3] &;

    theFile = File["result.txt"];

    Export[theFile, z1, "Table"];
)

I'm not sure if

 solution3d = wl.Get('test.m')
 s.evaluate(Global.solution3d(edges, vd, vl, ew))

this right, nothing is written to the txt file unfortunately. Could you please have a look?

[DeepaMahm]

@DbxDev This is a kind reminder

[DbxDev]

This goes beyond the scope of this ticket and should rather be discussed on stackoverflow.

You're confusing Wolfram Language representation in Python and actual code evaluation. The python code solution3d = wl.Get('test.m') represents a WL expression that is never evaluated and should be replaced with s.evaluate(wl.Get('test.m')). It'll declare the WL function Global`solution3d for the given session that you're using afterward.

Remember that WL code declared in Python (using wl.xxx syntax) must be evaluated in a session using (session.evaluate(...)) otherwise it stays inert!

[DeepaMahm]

@DbxDev Thank you. Unfortunately, I couldn't run it successfully after making the change that has been suggested. I have opened a new thread on stackoverflow as you suggested.