Introduce WindTurbineGroup as dataclass

This has the advantage that it is easier to find in the documentation.

tests/test_wind_turbine.py

@@ -8,9 +8,9 @@
 import pytest
 import os
 from windpowerlib.tools import WindpowerlibUserWarning
-from collections import namedtuple
+
 from windpowerlib.wind_turbine import (get_turbine_data_from_file, WindTurbine,
-                                       get_turbine_types,
+                                       get_turbine_types, WindTurbineGroup,
                                        load_turbine_data_from_oedb)
 
 
@@ -62,7 +62,7 @@ def test_to_group_method(self):
            'turbine_type': 'DUMMY 3',
            'path': self.source}
         e_t_1 = WindTurbine(**example_turbine)
-        assert(isinstance(e_t_1.to_group(), tuple))
+        assert(isinstance(e_t_1.to_group(), WindTurbineGroup))
         assert(e_t_1.to_group(5).number_of_turbines == 5)
         assert(e_t_1.to_group(number_turbines=5).number_of_turbines == 5)
         assert(e_t_1.to_group(total_capacity=3e6).number_of_turbines == 2.0)

windpowerlib/wind_farm.py

@@ -22,12 +22,17 @@ class WindFarm(object):
     Parameters
     ----------
     wind_turbine_fleet : :pandas:`pandas.DataFrame<frame>` or list()
-        Wind turbines of wind farm. DataFrame/Dictionaries must have
+        Wind turbines of wind farm. DataFrame must have
         'wind_turbine' containing a :class:`~.wind_turbine.WindTurbine` object
         and either 'number_of_turbines' (number of wind turbines of the same
         turbine type in the wind farm, can be a float) or 'total_capacity'
         (installed capacity of wind turbines of the same turbine type in the
         wind farm) as columns/keys. See example below.
+
+        A list of :class:`~windpowerlib.wind_turbine.WindTurbineGroup` objects.
+        A WindTurbineGroup can be created from a
+        :class:`~windpowerlib.wind_turbine.WindTurbine` using the
+        :func:`~windpowerlib.wind_turbine.WindTurbine.to_group` method.
     efficiency : float or :pandas:`pandas.DataFrame<frame>` or None (optional)
         Efficiency of the wind farm. Provide as either constant (float) or
         power efficiency curve (pd.DataFrame) containing 'wind_speed' and

windpowerlib/wind_turbine.py

@@ -13,8 +13,8 @@
 import warnings
 import requests
 import os
-from collections import namedtuple
 from windpowerlib.tools import WindpowerlibUserWarning
+from typing import NamedTuple
 
 
 class WindTurbine(object):
@@ -199,11 +199,14 @@ def __repr__(self):
         return turbine_repr
 
     def to_group(self, number_turbines=None, total_capacity=None):
-        """
-        Creates a WindTurbine group as a dictionary with the keys
-        'number_of_turbines' and 'wind_turbine'. It can be used to calculate
-        the number of turbines for a given total capacity or to create a
-        dictionary that can be used to define a WindFarm object.
+        r"""
+        Creates a :class:`~windpowerlib.wind_turbine.WindTurbineGroup`, a
+        NamedTuple data container with the fields 'number_of_turbines' and
+        'wind_turbine'.
+
+        It can be used to calculate the number of turbines for a given total
+        capacity or to create a namedtuple that can be used to define a
+        :class:`~windpowerlib.wind_farm.WindFarm` object.
 
         Parameters
         ----------
@@ -214,7 +217,7 @@ def to_group(self, number_turbines=None, total_capacity=None):
 
         Returns
         -------
-        namedtuple
+        WindTurbineGroup
             A namedtuple with two fields: 'number_of_turbines' and
             'wind_turbine'.
 
@@ -253,12 +256,24 @@ def to_group(self, number_turbines=None, total_capacity=None):
             number_turbines = total_capacity / self.nominal_power
         elif number_turbines is None:
             number_turbines = 1
-        wind_turbine_group = namedtuple('WindTurbineGroup',
-                                        'wind_turbine number_of_turbines')
-        return wind_turbine_group(
+
+        return WindTurbineGroup(
             wind_turbine=self, number_of_turbines=number_turbines)
 
 
+# This is working for Python >= 3.5.
+# There a cleaner solutions for Python >= 3.6, once the support of 3.5 is
+# dropped: https://stackoverflow.com/a/50038614
+class WindTurbineGroup(NamedTuple('WindTurbineGroup', [
+        ('wind_turbine', WindTurbine), ('number_of_turbines', float)])):
+    """
+    A simple data container to define more than one turbine of the same type.
+    Use the :func:`~windpowerlib.wind_turbine.WindTurbine.to_group` method to
+    easily create a WindTurbineGroup from a :class:`~windpowerlib.wind_turbine.WindTurbine` object.
+    """
+    __slots__ = ()
+
+
 def get_turbine_data_from_file(turbine_type, path):
     r"""
     Fetches turbine data from a csv file.