Fix NotFittedError

✅ Solution

The "NotFittedError" in scikit-learn usually arises when you try to use a transformer or estimator (like a pipeline, scaler, or model) before calling its `fit` method to train it on data. To fix this, ensure you call the `fit` method on your transformer/estimator object, passing it the appropriate training data (X, and optionally y for supervised models) before using it for transformation or prediction. For pipelines, fitting the pipeline fits all its constituent steps.