Performing feature engineering
Time, effort, and imagination are central to the process of feature engineering, which involves applying subject-matter expertise to create new features for prediction. In simple terms, it might be described as the art of making data more useful. In more complex terms, it involves a combination of domain expertise and data transformations. One needs to know not just what data will be useful to gather for the machine learning project, but also how to merge, code, and clean the data to conform to the algorithm’s expectations.
Feature engineering is closely interrelated with data exploration, as described in Chapter 11, Being Successful with Machine Learning. Both involve interrogating data through the generation and testing of hypotheses. Exploring and brainstorming are likely to lead to insights about which features will be useful for prediction, and the act of engineering the features may lead to new questions to explore.
Figure 12...