v0.3.0

Major updates to validation and feature engineering

validate_dataframe function has been updated to allow customising validation by allowing the user to set column validation to be skipped entirely or to be modified. This should help temporarily bypass significant DQ issues with SNOMED codes but should be used sparingly.

Feature maps have been reconfigured to make maintenance easier. As part of this multiple strategies for dealing with missing and unmapped codes have been implemented. Read the documentation on error codes for more information and mitigation steps.

Documentation has been updated to reflect these changes.