Concatenate list error Gradient descent Python

Question

I'm trying to solve this exercise about gradient descent. When I run my code I get an error on yi_pred = xi * m + c . Can someone please help me understand where I'm doing wrong? Thanks

def gradient_descent(x, y, m, c, epochs, L=0.001):
  x_new =[]
  for elem in x:
      x_new.extend(elem)
      y =[]
  for i in range(epochs):
          DM = []
          DC = []
          for num, xi in enumerate(x):
              yi_pred = xi * m + c
              yi = y[num]
              di_m = xi * (yi_pred - yi)
              di_c = yi_pred - yi
              DM.append(di_m)
              DC.append(di_c)
              dm = sum(DM)/len(DM)
              dc = sum(DC)/len(DC)
          m = m - L * dm
          c = c - L * dc

  return m,c```
Data:
x = [[0.18], [1.0], [0.92], [0.07], [0.85], [0.99], [0.87]]
y = [[109.85], [155.72], [137.66], [76.17], [139.75], [162.6], [151.77]]
m = 0
c = 0
epochs = 200

The error is: `TypeError: can only concatenate list (not "int") to list`. 

Answer 1

You are using a nested list.

Remove the extra square brackets '[]' from x and y :

x = [0.18, 1.0, 0.92, 0.07, 0.85, 0.99, 0.87]
y = [109.85, 155.72, 137.66, 76.17, 139.75, 162.6, 151.77]