如何在使用来自父对象的数据时更改父/子类结构的不同方法调用的代码

Question

(sorry if my title isn't concise enough)

I read data from binary simulation output, do some calculation and create different plots. The OO code I came up with works, but I'm not satisfied with the style and could use some advise. Here is my (simplified) code so far (find explanations below):

import numpy as np
import matplotlib.pyplot as plt

class TR:
    
    def __init__(self):
        self.t = np.linspace(0,10,100) # time
        self.x = np.sin(self.t)        # x data
        self.y = np.cos(self.t)        # y data

    # Base class
    class PostProcessor:
        
        def __init__(self, parent):
            self.parent = parent
            self.calc()
        
        def calc(self):
            # Define x_data and y_data in sub class
            pass
        
        def write(self):
            # Writes public attributes to file
            pass
        
        def read(self):
            # Reads class specific file
            pass
        
        def plot(self):
            # By default plot y_data over x_data
            fig = plt.figure()
            self.ax = fig.add_subplot(1, 1, 1)
            self.ax.plot(self.x_data, self.y_data)
            
            
    class Orbit(PostProcessor):
        
        def calc(self):
            self.x_data = self.parent.x
            self.y_data = self.parent.y
            
    class Response(PostProcessor):
        
        def calc(self):
            self.x_data = self.parent.t
            self.y_data = np.array([self.parent.x, self.parent.y]).transpose()

I created a class TR which is dedicated to one binary file. In my example I just provided the data ( t , x , y ) within the __init__ function.

For each plot (here: xy-Orbit and Response) I want to write to and read from a new file, because the raw data is quite huge and I just need chunks of it. To avoid duplicated code I created a base class PostProcessor which assigns the parent object (the TR object), provides a write , read and plot function.

This way the sub classes Orbit and Response only have to provide x_data and y_data.

This is how I use my code:

obj = TR()
obj.Orbit(obj).plot()
obj.Response(obj).plot()

Does somebody has an idea how to change the code so that I can use it as follows:?

obj = TR()
obj.Orbit.plot()
obj.Response.plot()

The problem is that I need to access data from the TR object and therefore I need to reference it with initialization.

I know it is not good that the plot function relies on the existance of self.x_data and self.y_data , but I got some error handling for it.

Answer 1

You could utilize properties.

class TR:
    def __init__(self):
        <your code>
        self._orbit = None
        self._response = None

    @property
    def orbit(self):
        if self._orbit is None:
            self._orbit = Orbit(self)
        return self._orbit

    @property
    def response(self):
        <same as for orbit>

Define classes Orbit() and Response() inline, no need to define them within PR and everything should work. No changes to classes themselves needed.

Now you can use it like this:

pr = PR()
pr.orbit.plot()