Class: Arrow::DataType

Inherits:
Object
  • Object
show all
Defined in:
lib/arrow/data-type.rb

Class Method Summary collapse

Class Method Details

.resolve(data_type) ⇒ Arrow::DataType .resolve(name, *arguments) ⇒ Object .resolve(description) ⇒ Object

Creates a new suitable Arrow::DataType.

Overloads:

  • .resolve(data_type) ⇒ Arrow::DataType

    Returns the given data type itself. This is convenient to use this method as Arrow::DataType converter.

    Parameters:

    Returns:

  • .resolve(name, *arguments) ⇒ Object

    Creates a suitable data type from type name. For example, you can create BooleanDataType from ‘:boolean`.

    Examples:

    Create a boolean data type

    Arrow::DataType.resolve(:boolean)

    Create a milliseconds unit timestamp data type

    Arrow::DataType.resolve(:timestamp, :milli)

    Parameters:

    • name (String, Symbol) —

      The type name of the data type.

    • arguments (::Array) —

      The additional information of the data type.

      For example, TimestampDataType needs unit as additional information.

  • .resolve(description) ⇒ Object

    Creates a suitable data type from data type description.

    Data type description is a raw ‘Hash`. Data type description must have `:type` value. `:type` is the type of the data type.

    If the type needs additional information, you need to specify it. See constructor document what information is needed. For example, ListDataType#initialize needs ‘:field` value.

    Examples:

    Create a boolean data type

    Arrow::DataType.resolve(type: :boolean)

    Create a list data type

    Arrow::DataType.resolve(type: :list,
                        field: {name: "visible", type: :boolean})

    Parameters:

    • description (Hash) —

      The description of the data type.

    Options Hash (description):

    • :type (String, Symbol) —

      The type name of the data type.



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# File 'lib/arrow/data-type.rb', line 74

def resolve(data_type)
  case data_type
  when DataType
    data_type
  when String, Symbol
    resolve_class(data_type).new
  when ::Array
    type, *arguments = data_type
    resolve_class(type).new(*arguments)
  when Hash
    type = nil
    description = {}
    data_type.each do |key, value|
      key = key.to_sym
      case key
      when :type
        type = value
      else
        description[key] = value
      end
    end
    if type.nil?
      message =
        "data type description must have :type value: #{data_type.inspect}"
      raise ArgumentError, message
    end
    data_type_class = resolve_class(type)
    if description.empty?
      data_type_class.new
    else
      data_type_class.new(description)
    end
  else
    message =
      "data type must be " +
      "Arrow::DataType, String, Symbol, [String, ...], [Symbol, ...] " +
      "{type: String, ...} or {type: Symbol, ...}: #{data_type.inspect}"
    raise ArgumentError, message
  end
end