Errata

Hands-On Machine Learning with Scikit-Learn and PyTorch

Errata for Hands-On Machine Learning with Scikit-Learn and PyTorch

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Color Key: Serious technical mistake Minor technical mistake Language or formatting error Typo Question Note Update

Version Location Description Submitted by Date submitted
O'Reilly learning platform Page toc
all

All TOC entries are randomly duplicated. It is at least twice too long, unusable.

 Anonymous  Oct 27, 2025 
O'Reilly learning platform Page Handling Text and Categorical Attributes
last para

df_output = pd.DataFrame(cat_encoder.transform(df_test_unknown),
... columns=cat_encoder.get_feature_names_out(),
... index=df_test_unknown.index)

results in error:
ValueError: Shape of passed values is (2, 1), indices imply (2, 5)

We should explicitly convert the sparse matrix returned by cat_encoder.transform() to a dense NumPy array using .toarray() before creating the DataFrame.

 Pradeep  Nov 14, 2025