How to assign the value to the mma variable when use the ExternalSession?

Question

Of course, I can use the this code:

session = StartExternalSession["Python"];
mmaVar1 = ExternalEvaluate[session, "a=[3,6,4];a"]

{3, 6, 4}

Then I can get a MMA variable mmaVar1, its name is assigned by Python. But I have to say it hard to write python code in a string line. So I like typing a > key into DefaultPythonSession:

But how to get the value of a in the DefaultPythonSession and assign to a MMA variable? This is my current method:

• Find the order of the DefaultPythonSession by ExternalSessions[]:

• Then

  mmaVar2 = ExternalEvaluate[ExternalSessions[][[2]], "a"]
  

Dirty solution...

Answer 1

You could get DefaultPythonSession directly by:

ExternalEvaluate`GetDefaultExternalSession["Python"]

or if you prefer using ExternalSessions by:

SelectFirst[ExternalSessions["Python"], #["Name"] === "DefaultPythonSession" &]

You should also note, that starting fresh Mathematica, will not start a python session automatically, so if you didn't start one, the first method return unevaluated command while in the second method, you have the option to return whatever you want (default is Missing["NotFound"]).