Python DataFrame or list for storing objects

Question

Can I "store" instances of class in pandas/numpy Series-DataFrame/ndarray just like I do in list? Or these libraries support on built-in types (numerics, strings).

For example I have Point with x,y coordinates, and I want to store Points in Plane, that would return Point with given coordinates.

#my class class MyPoint:      def __init__(self, x,y):         self.x = x         self.y = y      @property     def x(self):         return self.x      @property     def y(self):         return self.y 

Here I create instances:

first_point = MyClass(1,1) second_point = MyClass(2,2) 

I can store instances in some list

my_list = [] my_list.append(first_point) my_list.append(second_point) 

The problem in list is that it's indexes do not correspond to x,y properties.

Dictionary/DataFrame approach:

Plane = {"x" : [first_point.x, second_point.x], "y" : [first_point.y, second_point.y], "some_reference/id_to_point_instance" = ???} Plane_pd = pd.DataFrame(Plane) 

I've read posts, that using "id" of instance as third column value in DataFrame could cause problems with the garbage collector.

Answer 1

A pandas.DataFrame will gladly store python objects.

Some test code to demonstrate...

Test Code:

class MyPoint:     def __init__(self, x, y):         self._x = x         self._y = y      @property     def x(self):         return self._x      @property     def y(self):         return self._y  my_list = [MyPoint(1, 1), MyPoint(2, 2)] print(my_list)  plane_pd = pd.DataFrame([[p.x, p.y, p] for p in my_list],                         columns=list('XYO')) print(plane_pd.dtypes) print(plane_pd) 

Results:

[<__main__.MyPoint object at 0x033D2AF0>, <__main__.MyPoint object at 0x033D2B10>]  X     int64 Y     int64 O    object dtype: object     X  Y                                        O 0  1  1  <__main__.MyPoint object at 0x033D2AF0> 1  2  2  <__main__.MyPoint object at 0x033D2B10> 

Notes:

Note the two object in the list are the same two objects in the dataframe. Also note the dtype for the O column is object.