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https://issues.apache.org/jira/browse/SPARK-26738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16753867#comment-16753867
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Hyukjin Kwon commented on SPARK-26738:
--------------------------------------
Questions should go to mailing list. Let's ask a question there before filing
an issue here. You could have a better answer there.
> Pyspark random forest classifier feature importance with column names
> ---------------------------------------------------------------------
>
> Key: SPARK-26738
> URL: https://issues.apache.org/jira/browse/SPARK-26738
> Project: Spark
> Issue Type: Question
> Components: ML
> Affects Versions: 2.3.2
> Reporter: Praveen
> Priority: Major
> Labels: RandomForest, pyspark
>
> I am trying to plot the feature importances of random forest classifier with
> with column names. I am using Spark 2.3.2 and Pyspark.
> The input X is sentences and i am using tfidf (HashingTF + IDF) +
> StringIndexer to generate the feature vectors.
> I have included all the stages in a Pipeline
>
> {code:java}
> regexTokenizer = RegexTokenizer(gaps=False, inputCol= raw_data_col,
> outputCol= "words", pattern="[a-zA-Z_]+", toLowercase=True,
> minTokenLength=minimum_token_size)
> hashingTF = HashingTF(inputCol="words", outputCol="rawFeatures",
> numFeatures=number_of_feature)
> idf = IDF(inputCol="rawFeatures", outputCol= feature_vec_col)
> indexer = StringIndexer(inputCol= label_col_name, outputCol= label_vec_name)
> converter = IndexToString(inputCol='prediction', outputCol="original_label",
> labels=indexer.fit(df).labels)
> feature_pipeline = Pipeline(stages=[regexTokenizer, hashingTF, idf, indexer])
> estimator = RandomForestClassifier(labelCol=label_col,
> featuresCol=features_col, numTrees=100)
> pipeline = Pipeline(stages=[feature_pipeline, estimator, converter])
> model = pipeline.fit(df)
> {code}
> Generating the feature importances as
> {code:java}
> rdc = model.stages[-2]
> print (rdc.featureImportances)
> {code}
> So far so good, but when i try to map the feature importances to the feature
> columns as below
> {code:java}
> attrs = sorted((attr["idx"], attr["name"]) for attr in
> (chain(*df_pred.schema["featurescol"].metadata["ml_attr"]["attrs"].values())))
> [(name, rdc.featureImportances[idx])
> for idx, name in attrs
> if dtModel_1.featureImportances[idx]]{code}
>
> I get the key error on ml_attr
> {code:java}
> KeyError: 'ml_attr'{code}
> The printed the dictionary,
> {code:java}
> print (df_pred.schema["featurescol"].metadata){code}
> and it's empty {}
> Any thoughts on what I am doing wrong ? How can I getting feature importances
> to the columns names.
> Thanks
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