problem2.py

"""
# Execution
## $ python3 problem2.py input2.csv output2.csv
### This should generate an output file called output2.csv. There are ten cases in total, nine with the specified learning rates (and 100 iterations), and one with your own choice of learning rate (and your choice of number of iterations). After each of these ten runs, your program must print a new line to the output file, containing a comma-separated list of alpha, number_of_iterations, b_0, b_age, and b_weight in that order (see example), please do not round you your numbers. These represent the regression models that your gradient descents have computed for the given dataset.

### For the output, please follow the exact format, with no extra commas, change in upper/lower case etc. Extra unnecessary commas may make the automated script fail and result in you losing points.

### What To Submit. problem2.py, which should behave as specified above. Before you submit, the RUN button on Vocareum should help you determine whether or not your program executes correctly on the platform.

"""

# builtin modules
import os
import psutil
import requests
import sys
import math


# 3rd party modules
import pandas as pd
import numpy as np
#import plotly.graph_objects as go


# Prepare data

def get_data(source_file:str = 'input2.csv'):

# Define input and output filepaths
    input_path = os.path.join(os.getcwd(),'datasets','in', source_file)

    # Read input data
    df = pd.read_csv(input_path)
    
    for col in df.columns:
        df[col] = (df[col] - np.mean(df[col]))/np.std(df[col])
        #note: numpy.std returns the population standard deviation
    return df


def gradient_descent(df=df, iterations:int = 100, learning_rates:tuple = (0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, 10)):

    """
    X:dataframe of feature columns: age and weight
    y: dataframe of label column: height
    beta:
    learning_rate: 
    iterations: 
    """
    df = pd.concat([pd.Series(1, index=df.index, name='b_0'), df], axis=1)
    
    X = df[df.columns[0:3]].values

    y = df[df.columns[3]].to_numpy()
    #y = y[:, np.newaxis]

    m = y.shape[0]
    betas = np.zeros(X.shape[1]) #initialize betas as zeros, e.g. array([0., 0., 0.])
    betas_new =[]

    for alfa in learning_rates:
        i = 0
        while i < iterations:
            hypothesis = np.dot(X, betas)
            #hypothesis = hypothesis.reshape(hypothesis.shape[0],1)
            betas = betas - (1/m) * alfa *(X.T.dot((hypothesis - y)))
            i += 1
        betas_new.append(betas)

    return betas_new
 
def write_csv(filename:str='output2.csv', betas_new:list = betas_new, iterations:int = 100, learning_rates:tuple = (0.001, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, 10)):
        # write the outputs csv file
        filepath = os.path.join(os.getcwd(),'datasets','out', filename)
        iter_array = np.full(len(learning_rates), iterations)
        df_iter = pd.DataFrame(iter_array)
        df_lr = pd.DataFrame(learning_rates)
        df_b = pd.DataFrame(betas_new)
        df_final = pd.concat([df_lr, df_iter, df_b], axis = 1, ignore_index = True)
        dataframe = df_final.rename(columns={0:'alpha',1:'number_of_iterations',2:'b_0', 3:'b_age',4:'b_weight'})
        dataframe.to_csv(filepath, index = False, header = False)
        return print("New Outputs file saved to: <<", filename, ">>", sep='', end='\n')


def main():
    """
    ## $ python3 problem2.py input2.csv output2.csv
    """
    #take string for input data csv file
    in_data = str(sys.argv[1])
    #take string for output data csv file
    out_data = str(sys.argv[2])

    df = get_data(in_data)
    betas_new = gradient_descent(df)
    write_csv(out_data, betas_new)

if __name__ == '__main__':
    main()