Databricks Machine Learning Associate Question 374
Select 2A retail company is analyzing sales data and wants to train group-specific machine learning models for each store to predict monthly sales. The dataset is stored as a Spark DataFrame and contains columns: 'store_id', 'month', 'sales', and 'features'. Which of the following methods should be used to train and apply group-specific models efficiently?
- A
Use the Pandas Function API by defining a function to train a model for each group and applying it with groupby on 'store_id'.
- B
Use Spark's built-in MLlib algorithm to train a single global model instead of group-specific models.
- C
Convert the Spark DataFrame to a Pandas DataFrame, and manually loop through each unique 'store_id' to train a model for each group.
- D
Use the Pandas Function API with groupby on 'store_id' and pass a UDF to train the models for each group.
- E
Leverage the Pandas Function API to create a grouped map Pandas UDF for efficient group-specific model training and application.
Show answer and explanation
Correct answers: A, E
Explanation
The Pandas Function API is an efficient and scalable method to handle group-specific tasks in distributed environments like Spark. By using a grouped map Pandas UDF, you can define custom logic to train and apply machine learning models for each group, such as 'store_id', while leveraging Spark's distributed processing. This avoids the inefficiencies of manual loops or global models, making it the best approach for the given scenario.
- A. Correct.
Correct: The Pandas Function API allows you to define custom Python logic for grouped data processing, making it ideal for training group-specific models by leveraging Spark's distributed computation.
- B. Incorrect.
Incorrect: Training a single global model does not fulfill the requirement to create group-specific models for each store. This approach is not suitable for the scenario.
- C. Incorrect.
Incorrect: While it is possible to manually loop through each group in a Pandas DataFrame, this approach is inefficient and does not leverage Spark's distributed processing capabilities.
- D. Incorrect.
Incorrect: Using a UDF for this task is not recommended, as UDFs are not designed for group-specific processing and are less efficient compared to the Pandas Function API.
- E. Correct.
Correct: The Pandas Function API's grouped map Pandas UDF is specifically designed for distributed group-specific processing, enabling efficient training and application of models for each group.