Motivation

Partially addresses #8. Sequences (lists and arrays) are compared element-wise, iterating over each position in the sequence. Each element is then compared using the standard type-aware logic, so absolute/relative float tolerances and absolute temporal tolerances all apply naturally.

Maximum sequence length

An array's length (or shape for multi-dimensional arrays) is known statically from its data type. When at least one of the two compared columns is an array, its length determines the number of elements to compare. When both columns are lists, the maximum list length must be computed at runtime — this is handled by the cached property _max_list_lengths_by_column, a dictionary mapping column names to their maximum list length, populated only for columns that are pl.List in both data frames. The resolved max_list_length: int | None is then passed to condition_equal_columns().

Sequences of different lengths

Arrays have a fixed length, so comparing two arrays of different shapes can immediately return False. In all other cases, lengths may vary row-by-row, which is captured in the has_same_length expression. To avoid out-of-bound errors when indexing into shorter lists, null_on_oob=True is used instead of raising. The final result combines has_same_length with elements_match (the element-wise comparison), so rows with mismatched lengths are marked as unequal.

Multi-dimensional sequences

Nested sequences (e.g., lists of lists or multi-dimensional arrays) are handled recursively: outer elements are extracted positionally, then compared via the same _compare_columns logic until primitive types are reached. When both sides are lists at an inner nesting level, no max_list_length is available, so the comparison falls back to direct equality without element-wise unrolling (i.e., tolerances do not apply at inner list levels).

Changes

• add cached property _max_list_lengths_by_column: dict[str, int]
• introduce function _compare_sequence_columns() to compare lists and arrays with each other
• add extensive test coverage
  • Modify test_condition_equal_columns_list_array_{equal_exact -> with_tolerance} to reflect the updated logic
  • Build on the former test with nested sequence types in test_condition_equal_columns_nested_list_array_with_tolerance
  • test comparison of two list columns in test_condition_equal_columns_two_lists, including empty lists, lists with None and None
  • cover mismatches of lengths in test_condition_equal_columns_array_vs_list_length_mismatch
  • cover mismatching array shapes in test_condition_equal_columns_two_arrays_different_shapes
  • handle the edge case of empty arrays and lists in test_condition_equal_columns_empty_arrays and test_condition_equal_columns_empty_lists, respectively