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How Badly Does This Java Class Need Refactoring?

From size and complexity metrics, how severe is this class's data-class smell, a class that holds data but does little with it? Teams use the score to decide what to clean up first.

Use caseTechnologyPredictionModel evaluation

The table

Java classes from open-source projects with size, coupling and complexity metrics, and a severity score for the data-class smell. It's in Welt's research catalogue as Code Smells Data Class, 86,467 rows by 74 columns, licensed Public. The catalogue measures its signal at 0.37. At 86,467 rows and 73 features the table is larger than the model limits allow, so the walkthrough evaluates and fits on a seeded sample of 2,000 rows. TabICLv2 and Kumo Tabular Medium compete.

Walkthrough

  1. Load it from the catalogue

    Find the table, read its recorded target and print the column names.

    import pandas as pd
    from welt import Client
    
    with Client() as client:
        item = client.research_datasets(q="code smells data class", limit=1)["items"][0]
        info = client.research_dataset(item["id"])
        data = client.load_research_dataset(item["id"])
    
    target = info["targets"][0]
    target = target["name"] if isinstance(target, dict) else target
    print([column["name"] for column in info["schema"]], target)
  2. Pick the rows

    Set aside 20 rows to predict at the end. The models learn from a seeded sample of 2,000 of the rest, the most this table's width allows.

    known = data.dropna(subset=[target])
    new_rows = known.sample(20, random_state=1)
    table = known.drop(new_rows.index).sample(2000, random_state=7)
  3. Compare the models and predict

    The models compete on the same folds against a simple guess, then the top-ranked one is fitted on the whole table. RMSE and MAE are average errors in the target's own units, so lower is better. The last table puts each prediction next to the real answer.

    with Client() as client:
        evaluation = client.evaluate(table, target, task="regression", seed=7,
                                     models=["tabicl-v2", "kumo-medium"])
        model = evaluation.fit()
    
    print(evaluation.summary()[["name", "rank", "rmse_mean", "mae_mean"]])
    features = new_rows.drop(columns=target)
    print(pd.DataFrame({"actual": new_rows[target].values, "predicted": model.predict(features)}))

What you get

A severity per classRank the codebase for refactoring.
Wide tables handledSeventy-three metrics go in without selection.
An honest signalThe catalogue measures a modest signal.

Try it

Use Open with to run the research datasets notebook in Colab, Kaggle or Jupyter and search for "code smells data class", or run the code above after pip install "welt-client[parquet]".