Expression translator should support multi-dimensional array indexing syntax

スタックトレースで特定された org.jpmml.python.ExpressionTranslator から始め、X["c2"][0] を使った ExpressionTransformer の例で失敗を再現してください。StringSlicingExpression の parser による処理を追跡し、PMML 変換が多次元配列のインデックス指定を受け入れることを確認してください。報告された pipeline は IllegalArgumentException なしで変換されるはずです。

Hi, I have a scanrio where I need to use an array as a input column to my pipeline.
I'd reduced a minimal example of the issue I'm having:

import pandas as pd
from sklearn.linear_model import LogisticRegression
from sklearn.pipeline import make_pipeline
from sklearn.compose import ColumnTransformer
from sklearn2pmml.preprocessing import ExpressionTransformer

df = pd.DataFrame({'c1': [1, 2, 3], 'c2': [[1,2], [1,2], [3,1]]})

pipeline = make_pipeline(
    ColumnTransformer(
        transformers=[
            (f'get_item_0_from_c2_array', ExpressionTransformer('X["c2"][0]'), ['c2'])
        ]
    ),
    LogisticRegression(),
)
pipeline.fit(df, [0, 0, 1])
pipeline.predict(df)

The above pipeline works fine in my jupyter notebook. But converting it to a PMML gives an error:

import sklearn2pmml

pmml_pipeline = sklearn2pmml.PMMLPipeline(steps=[
    ('pipeline',pipeline)
])

sklearn2pmml.sklearn2pmml(pmml_pipeline, './pipeline.pmml', debug=True)

Gives the error:

java.lang.IllegalArgumentException: Python expression 'X["c2"][0]' is either invalid or not supported
	at org.jpmml.python.ExpressionTranslator.translate(ExpressionTranslator.java:36)
	at org.jpmml.python.ExpressionTranslator.translate(ExpressionTranslator.java:23)
	at sklearn2pmml.preprocessing.ExpressionTransformer.encodeFeatures(ExpressionTransformer.java:51)
	at sklearn.Transformer.encode(Transformer.java:70)
	at sklearn.compose.ColumnTransformer.encodeFeatures(ColumnTransformer.java:63)
	at sklearn.Transformer.encode(Transformer.java:70)
	at sklearn.Composite.encodeFeatures(Composite.java:119)
	at sklearn.Composite.encodeModel(Composite.java:135)
	at sklearn.pipeline.PipelineClassifier.encodeModel(PipelineClassifier.java:86)
	at sklearn.Estimator.encode(Estimator.java:103)
	at sklearn2pmml.pipeline.PMMLPipeline.encodePMML(PMMLPipeline.java:233)
	at org.jpmml.sklearn.Main.run(Main.java:217)
	at org.jpmml.sklearn.Main.main(Main.java:143)
Caused by: org.jpmml.python.ParseException: Encountered unexpected token: "]" "]"
    at line 1, column 10.

Was expecting one of:

    ":"

	at org.jpmml.python.ExpressionTranslator.generateParseException(ExpressionTranslator.java:2110)
	at org.jpmml.python.ExpressionTranslator.jj_consume_token(ExpressionTranslator.java:1973)
	at org.jpmml.python.ExpressionTranslator.StringSlicingExpression(ExpressionTranslator.java:956)
	at org.jpmml.python.ExpressionTranslator.PrimaryExpression(ExpressionTranslator.java:637)
	at org.jpmml.python.ExpressionTranslator.UnaryExpression(ExpressionTranslator.java:597)
	at org.jpmml.python.ExpressionTranslator.MultiplicativeExpression(ExpressionTranslator.java:538)
	at org.jpmml.python.ExpressionTranslator.AdditiveExpression(ExpressionTranslator.java:494)
	at org.jpmml.python.ExpressionTranslator.ComparisonExpression(ExpressionTranslator.java:434)
	at org.jpmml.python.ExpressionTranslator.NegationExpression(ExpressionTranslator.java:389)
	at org.jpmml.python.ExpressionTranslator.LogicalAndExpression(ExpressionTranslator.java:359)
	at org.jpmml.python.ExpressionTranslator.LogicalOrExpression(ExpressionTranslator.java:338)
	at org.jpmml.python.ExpressionTranslator.IfElseExpression(ExpressionTranslator.java:319)
	at org.jpmml.python.ExpressionTranslator.Expression(ExpressionTranslator.java:312)
	at org.jpmml.python.ExpressionTranslator.translateExpressionInternal(ExpressionTranslator.java:306)
	at org.jpmml.python.ExpressionTranslator.translate(ExpressionTranslator.java:34)
	... 12 more