mysterious error message

[lewisl]

This is a fragment of the very long error message: expected return statement, got ($(QuoteNode(PyCall.pyimport)))("sklearn.tree")

This is the seemingly trivial code:

@sk_import ensemble: AdaBoostClassifier
@sk_import tree: DecisionTreeClassifier

function boost_tree(traindata)
    trainx = traindata[:,1:end-1]
    trainy = traindata[:,end]
    bdt = AdaBoostClassifier(base_estimator = DecisionTreeClassifier(max_depth=6), n_estimators=5)
    ScikitLearn.fit!(bdt, trainx, trainy)
    return bdt
end

No clue. Documentation is really tough to apply if you try anything slightly different than the examples. Translation from the Python doc to the Julia wrapper is definitely non-obvious.

[lewisl]

Somewhere I saw this little @macroexpand trick. It takes care of the problem with calling Python. Not clear why it's necessary and, if it is, why it's not documented explicitly:

using ScikitLearn

@macroexpand @sk_import ensemble: AdaBoostClassifier
@macroexpand @sk_import tree: DecisionTreeClassifier

function boost_tree(traindata)
    trainx = traindata[:,1:end-1]
    trainy = traindata[:,end]
    bdt = AdaBoostClassifier(DecisionTreeClassifier(max_depth=6), n_estimators=5) 
    ScikitLearn.fit!(bdt, trainx, trainy)
    return bdt
end

Now, I get the strange outcome that DecisionTreeClassifier is an undefined variable:

ERROR: UndefVarError: DecisionTreeClassifier not defined

[lewisl]

Further bizarreness. This all works when each line is entered in the REPL. So, this has to do with some namespace munging involving the macro expansion.

I'll note that there are a lot of deprecation warnings with this packages use of PyCall and the appropriate notation.

[cstjean]

Sorry, I haven't been able to put much time into this package recently. Contributions to the docs are welcome.

If you try the latest master, with ]add ScikitLearn#master, it should get rid of most of the deprecation warnings, at least. I'll try to look at the errors when I get a chance. You can always try to use PyCall (check its docs) directly to import the modules you want.

[cstjean]

Is this fixed on the latest version?