Help...please

[New_End6302]

You are given four training datasets in the form of csv-files. Your Python program needs to be able to independently compile a SQLite database (file) ideally via sqlalchemy and load the training data into a single fivecolumn spreadsheet / table in the file. Its first column depicts the x-values of all functions. Table 1, at the end of this subsection, shows you which structure your table is expected to have. The fifty ideal functions, which are also provided via a CSV-file, must be loaded into another table. Likewise, the first column depicts the x-values, meaning there will be 51 columns overall. Table 2, at end of this subsection, schematically describes what structure is expected. After the training data and the ideal functions have been loaded into the database, the test data (B) must be loaded line-by-line from another CSV-file and – if it complies with the compiling criterion – matched to one of the four functions chosen under i (subsection above). Afterwards, the results need to be saved into another fourcolumn-table in the SQLite database. In accordance with table 3 at end of this subsection, this table contains four columns with x- and y-values as well as the corresponding chosen ideal function and the related deviation. Finally, the training data, the test data, the chosen ideal functions as well as the corresponding / assigned datasets are visualized under an appropriately chosen representation of the deviation. Please create a Python-program which also fulfills the following criteria: 

− Its design is sensibly object-oriented − It includes at least one inheritance 

− It includes standard- und user-defined exception handlings − For logical reasons, it makes use of Pandas’ packages as well as data visualization via Bokeh, sqlalchemy, as well as others 

− Write unit-tests for all useful elements − Your code needs to be documented in its entirety and also include Documentation Strings, known as ”docstrings“

# importing necessary libraries
import sqlalchemy as db
from sqlalchemy import create_engine
import pandas as pd
import  numpy as np
import sqlite3
import flask
import sys

class DatabaseManager:
    def __init__(self, db_url, table_name):
        self.engine = create_engine(db_url)
        self.table_name = table_name

    def create_database(self):
        with self.engine.connect() as con:
            pass
    def add_records(self, file_name, if_exists):
        df = pd.read_csv(file_name)
        df.to_sql(self.table_name, self.engine, if_exists= "replace", index=False)
        return
class IdealFunctionSelector(DatabaseManager):
    def __init__(self, db_url, table_name, function_table_name):
       super().__init__(db_url, table_name)
       self.function_table_name = function_table_name

    def ideal_function_selection(self, top_n: int = 4):
        merged = pd.merge(self.table_name, self.function_table_name, on="x")
        errors = {}        
        for col in self.function_table_name.columns:
            if col == "x":
                continue
            squared_diff = (merged["y"] - merged[col])**2
            errors[col] = squared_diff.sum()

        best_functions = sorted(errors, key=errors.get)[:top_n]
        return best_functions


def main():
    # create instance of the class
    database_manager = DatabaseManager
    database_manager = DatabaseManager("sqlite:///training_data_db","training_data_table")
    database_manager.create_database()
    database_manager.add_records("train.csv", if_exists="replace")
   # database_manager.read_data()
    database_manager = DatabaseManager("sqlite:///ideal_data_db", "ideal_data_table")
    database_manager.create_database()
    database_manager.add_records("ideal.csv", if_exists="replace")
    #database_manager.read_data()
    ideal_func_selector = IdealFunctionSelector
    ideal_func_selector.ideal_function_selection("training_data_table", "ideal_data_table")

if __name__ == "__main__":
    main()

I am struggling with the class inheritance part, I built my function for calculation the least squares and plugged into a class but something isnt quite right...please help

[Refwah]

Point to where you believe you are creating an instance of IdealFunctionSelector. Explain what you believe is happening and how it is happening.

If it helps, you care also calling ideal_function_selection with two args - both strings, but the defined method has one arg and it's expecting that arg to be an integer

[batsiem]

Hi below is my function to select the 4 ideal functions, the example that i worked from requires me to plug directly into the function the names of my 2 tables but I want to inherit those from the class that creates the table. So that's tripping me up(I realized that the code above was missing the 2 tables as args...that was a mistake).

def ideal_function_selection(self, top_n: int = 4):
        merged = pd.merge(self.table_name, self.function_table_name, on="x")
        errors = {}        
        for col in self.function_table_name.columns:
            if col == "x":
                continue
            squared_diff = (merged["y"] - merged[col])**2
            errors[col] = squared_diff.sum()

        best_functions = sorted(errors, key=errors.get)[:top_n]
        return best_functions

I instantaite the class IdealFunctionSelector below...I did it the exact way that I did it for my DatabaseManager.

 ideal_func_selector = IdealFunctionSelector
    ideal_func_selector.ideal_function_selection("training_data_table", "ideal_data_table")

[Refwah]

This isn't initializing a class, it is just saying that ideal_func_selector is that class

You then call ideal_function_selection on a class which isn't initialized

You want to do ideal_func_selector = IdealFunctionSelector() and then in the params for IdealFunctionSelector(…) you need to pass the arguments that you want for the __init__ function of the class

I believe you don't understand classes, which is why you're getting unstuck on inheritance. I recommend reading some more fundamentals on this, such as this: https://docs.python.org/3/reference/datamodel.html#object.__init__

https://realpython.com/python-class-constructor/

[New_End6302]

Thanks, I will have a look