Arrow.
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A named column within a schema. Holds the logical type, nullability, an
optional per-field metadata map, the child fields used by nested types
(List, Struct), and an optional Arrow.Type.DictionaryEncoding when
the field is dictionary-encoded.
Dictionary encoding in Arrow is a property of the field, not a type:
the type continues to describe what the dictionary stores (e.g.
Utf8), while dictionary.index_type describes the integer type used
in record batches to reference dictionary entries.
Summary
Functions
Walks the field tree under schema_or_fields and returns the first
field whose dictionary annotation has the given id, or nil.
Returns the field with its dictionary annotation stripped — i.e. a
field that describes the value type only. Used when decoding the
contents of a DictionaryBatch, where the buffers carry the dictionary
values rather than indices.
Types
@type t() :: %Arrow.Field{ children: [t()], dictionary: Arrow.Type.DictionaryEncoding.t() | nil, metadata: metadata(), name: String.t(), nullable: boolean(), type: Arrow.Type.t() }
Functions
@spec find_by_dictionary_id(Arrow.Schema.t() | [t()], non_neg_integer()) :: t() | nil
Walks the field tree under schema_or_fields and returns the first
field whose dictionary annotation has the given id, or nil.
Returns the field with its dictionary annotation stripped — i.e. a
field that describes the value type only. Used when decoding the
contents of a DictionaryBatch, where the buffers carry the dictionary
values rather than indices.