Build a Practical Data Preparation and Splitting Example in Machine Learning Fundamentals

Define the build target

For Data Preparation and Splitting, define a prediction problem, create a leakage-safe split, build a baseline pipeline, and document the evaluation plan. Build the boundary case using this implementation lens: Use datasets, features, targets, train/validation/test splits, estimators, metrics, pipelines, error analysis, and reproducible model evaluation.

Keep the Data Preparation and Splitting build centered on these technical constraints: Target and unit of prediction. Data split strategy. Apply them through this path lens: Use datasets, features, targets, train/validation/test splits, estimators, metrics, pipelines, error analysis, and reproducible model evaluation. Use datasets, features, targets, train/validation/test splits, estimators, metrics, pipelines, error analysis, and reproducible model evaluation.

Implement the core behavior

Implement Data Preparation and Splitting around the module artifact—a working data preparation and splitting example with an explicit success and failure check—and keep the implementation specific to this path context: Use datasets, features, targets, train/validation/test splits, estimators, metrics, pipelines, error analysis, and reproducible model evaluation.

from sklearn.model_selection import train_test_split
from sklearn.pipeline import make_pipeline
from sklearn.impute import SimpleImputer
from sklearn.linear_model import LogisticRegression

X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, stratify=y, random_state=42)
pipeline = make_pipeline(SimpleImputer(), LogisticRegression(max_iter=1000))
pipeline.fit(X_train, y_train)
print('held-out accuracy:', pipeline.score(X_test, y_test))

python3 pipeline.py

A preprocessing/model pipeline evaluated on data that was not used for fitting.

practice/\n├── README.md\n├── data-preparation-and-splitting-build.py\n└── evidence/\n    └── expected-result.txt

Run the complete path

Run one realistic Data Preparation and Splitting case end to end and record the required evidence: the relevant output, test, log, query result, or rendered state for Data Preparation and Splitting. Interpret the result through this path context: Use datasets, features, targets, train/validation/test splits, estimators, metrics, pipelines, error analysis, and reproducible model evaluation.

Change one meaningful condition

Modify one condition central to Data Preparation and Splitting using this path context: Use datasets, features, targets, train/validation/test splits, estimators, metrics, pipelines, error analysis, and reproducible model evaluation. Predict the new result before rerunning the same workflow.

Verify the artifact

Your deliverable is a working data preparation and splitting example with an explicit success and failure check.

Common mistakes to avoid

• Target leakage.
• Random split violates time/group structure.
• Preprocessing fitted before split.
• Metric does not match decision need.