Add get_missing_summary helper for dataset missing values

[Faisalhakimi22]

Metadata

• Reference Issue: Closesget_missing_summary() helper method for OpenML datasets #1443
• New Tests Added: Yes
• Documentation Updated: Yes
• Change Log Entry: Add new helper method get_missing_summary() to OpenMLDataset class

Details

• What does this PR implement/fix?
  Implements a new helper method get_missing_summary() in the OpenMLDataset class, which returns a summary of missing values for a dataset, including total missing values and per-column counts.

• Why is this change necessary?
  Many users currently need to manually check for missing values after calling get_data(). This method simplifies dataset exploration, reduces repetitive code, and improves usability for both new and advanced users.

• How can I reproduce the issue this PR is solving and its solution?

import openml dataset = openml.datasets.get_dataset(31, download_data=True) summary = dataset.get_missing_summary() print(summary)