Class: Arrow::DataType

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

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.resolve(data_type) ⇒ Arrow::DataType .resolve(name) ⇒ Arrow::DataType .resolve(name_with_arguments) ⇒ Arrow::DataType .resolve(description) ⇒ Arrow::DataType

Ensure returning 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) ⇒ Arrow::DataType

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

    Examples:

    Create a boolean data type

    Arrow::DataType.resolve(:boolean)

    Parameters:

    • name (String, Symbol) —

      The type name of the data type.

    Returns:

  • .resolve(name_with_arguments) ⇒ Arrow::DataType

    Creates a new suitable data type from the given type name with arguments.

    Examples:

    Create a boolean data type

    Arrow::DataType.resolve([:boolean])

    Create a milliseconds unit timestamp data type

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

    Parameters:

    • name_with_arguments (::Array<String, ...>) —

      The type name of the data type as the first element.

      The rest elements are additional information of the data type.

      For example, TimestampDataType needs unit as additional information.

    Returns:

  • .resolve(description) ⇒ Arrow::DataType

    Creates a new suitable data type from the given 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.

    Returns:



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# File 'lib/arrow/data-type.rb', line 92

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? and self == DataType
      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

.sub_types ⇒ Object 



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# File 'lib/arrow/data-type.rb', line 133

def sub_types
  types = {}
  gtype.children.each do |child|
    sub_type = child.to_class
    types[sub_type] = true
    sub_type.sub_types.each do |sub_sub_type|
      types[sub_sub_type] = true
    end
  end
  types.keys
end

.try_convert(value) ⇒ Object 



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# File 'lib/arrow/data-type.rb', line 145

def try_convert(value)
  begin
    resolve(value)
  rescue ArgumentError
    nil
  end
end

Instance Method Details

#array_class ⇒ Object 



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# File 'lib/arrow/data-type.rb', line 191

def array_class
  base_name = self.class.name.gsub(/DataType\z/, "")
  ::Arrow.const_get("#{base_name}Array")
end

#build_array(values) ⇒ Object 



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# File 'lib/arrow/data-type.rb', line 196

def build_array(values)
  builder_class = array_class.builder_class
  args = [values]
  args.unshift(self) unless builder_class.buildable?(args)
  builder_class.build(*args)
end

#scalar_class ⇒ Arrow::Scalar

Returns A corresponding Scalar class for this data type.

Returns:

Since:

  • 12.0.0



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# File 'lib/arrow/data-type.rb', line 207

def scalar_class
  base_name = self.class.name.gsub(/DataType\z/, "")
  ::Arrow.const_get("#{base_name}Scalar")
end