Evaluate OutlierHandler Class for Code Quality and Testing

Q: Evaluate OutlierHandler Class for Code Quality and Testing

This question evaluates a candidate's competence in machine-learning data preprocessing, scikit-learn-style transformer API design, unit testing, and code quality assessment including PEP-8 and maintainability concerns.

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Question

Code Review: OutlierHandler and Imputer Classes

Context

You are given a Python module that implements one OutlierHandler class and three Imputer classes for preprocessing tabular data. The classes appear to be intended for use in machine-learning pipelines (e.g., scikit-learn style), but the code has mixed style and testing coverage.

Assumptions to make the question self-contained:

OutlierHandler detects outliers per feature using a rule such as IQR capping (Q1 − 1.5×IQR, Q3 + 1.5×IQR) or z-score thresholds and caps or replaces outliers during transform.
Each Imputer learns a statistic on fit (e.g., mean/median/mode/constant) and fills missing values during transform.

Tasks

Provide a high-level summary of what the OutlierHandler class does.
Explain why separating fit and transform into two methods is beneficial in this context.
Identify coding-style and maintainability issues in the file (naming, docstrings, magic numbers, etc.).
Propose the single most critical unit test you would add for OutlierHandler.
For the three imputation classes, describe their overall purpose and identify at least two style problems (e.g., use of from numpy import * ).

Hints: Relate your answers to the scikit-learn transformer API, unit-testing best practices, and PEP-8.

Evaluate OutlierHandler Class for Code Quality and Testing

Code Review: OutlierHandler and Imputer Classes

Context

Tasks

Solution

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