Confusion between Supervised Regression LESSON and Supervised Regression PROJECT

So I learned how to build a linear regression model manually in the “Build a Machine Learning Model” skill path, specifically in the “Supervised Learning: Regression” module, and more specifically in the “Linear Regression” lesson (https://www.codecademy.com/paths/machine-learning/tracks/regression-skill-path/modules/linear-regression-skill-path/lessons/linear-regression/exercises/introduction).

Using the information I learned in the lesson, I created the following code chunk:

import matplotlib.pyplot as plt

def get_gradient_at_b(x, y, b, m):

  N = len(x)

  diff = 0

  for i in range(N):

    x_val = x[i]

    y_val = y[i]

    diff += (y_val - ((m * x_val) + b))

  b_gradient = -(2/N) * diff  

  return b_gradient

def get_gradient_at_m(x, y, b, m):

  N = len(x)

  diff = 0

  for i in range(N):

      x_val = x[i]

      y_val = y[i]

      diff += x_val * (y_val - ((m * x_val) + b))

  m_gradient = -(2/N) * diff  

  return m_gradient

#Your step_gradient function here

def step_gradient(b_current, m_current, x, y, learning_rate):

    b_gradient = get_gradient_at_b(x, y, b_current, m_current)

    m_gradient = get_gradient_at_m(x, y, b_current, m_current)

    b = b_current - (learning_rate * b_gradient)

    m = m_current - (learning_rate * m_gradient)

    return [b, m]

  

#Your gradient_descent function here:  

def gradient_descent(x, y, learning_rate, num_iterations):

  b = 0

  m = 0

  for i in range(num_iterations):

    b,m = step_gradient(b, m, x, y, learning_rate)

  return [b,m]

  

months = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

revenue = [52, 74, 79, 95, 115, 110, 129, 126, 147, 146, 156, 184]

#Uncomment the line below to run your gradient_descent function

b, m = gradient_descent(months, revenue, 0.01, 1000)

#Uncomment the lines below to see the line you've settled upon!

y = [m*x + b for x in months]

plt.plot(months, revenue, "o")

plt.plot(months, y)

plt.show()

And this code chunk does very well and generates me a nice looking scatterplot with a line of best fit:
image
Now, my problem arises when I get to the corresponding project to this lesson. In the project you are advised to use a prewritten regression model from the SKLearn library, which is fine, but I was curious to see if the one I had used in the previous lesson would work for this problem. So I tried to use the one codecademy had taught me to create myself, but the line wouldn’t generate, saying the B, and M were not numbers (nan). I was wondering why this is the case? I’ve been troubleshooting for a few hours and I feel I did a good job of implementing the model I was taught to make on the data from this project.

Here it is below, does anyone have an idea as to why this doesn’t generate me a line of best fit?

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd


def get_gradient_at_b(x, y, b, m):
  N = len(x)
  diff = 0
  for i in range(N):
    x_val = x[i]
    y_val = y[i]
    diff += (y_val - ((m * x_val) + b))
  b_gradient = -(2/N) * diff  
  return b_gradient

def get_gradient_at_m(x, y, b, m):
  N = len(x)
  diff = 0
  for i in range(N):
      x_val = x[i]
      y_val = y[i]
      diff += x_val * (y_val - ((m * x_val) + b))
  m_gradient = -(2/N) * diff  
  return m_gradient

def step_gradient(b_current, m_current, x, y, learning_rate):
    b_gradient = get_gradient_at_b(x, y, b_current, m_current)
    m_gradient = get_gradient_at_m(x, y, b_current, m_current)
    b = b_current - (learning_rate * b_gradient)
    m = m_current - (learning_rate * m_gradient)
    return [b, m]
  
def gradient_descent(x, y, learning_rate, num_iterations):
  b = 0
  m = 0
  for i in range(num_iterations):
    b,m = step_gradient(b, m, x, y, learning_rate)
  return [b,m]



df = pd.read_csv('honeyproduction.csv')

prod_per_year = df.groupby('year').mean().reset_index()

X = prod_per_year['year']

X = X.values.reshape(-1, 1)

y = prod_per_year['totalprod']

b, m = gradient_descent(X, y, 0.01, 1000)

y_predictions = [m*x + b for x in X]

plt.plot(X,y,'o')

plt.plot(X,y_predictions)

plt.xlabel("Years")

plt.ylabel("HoneyBee Production Per Year (Lbs)")

plt.show()

It just spits the scatterplot out with no line.