# Issue in Programming Assignment: Collaborative Filtering Recommender Systems

I am facing issue in with regularization code . exactly where and how to put the with regularization code . I checked the hints also but not getting it. please anyone solve my problm.

# UNQ_C1

def cofi_cost_func(X, W, b, Y, R, lambda_):
“”"
Returns the cost for the content-based filtering
Args:
X (ndarray (num_movies,num_features)): matrix of item features
W (ndarray (num_users,num_features)) : matrix of user parameters
b (ndarray (1, num_users) : vector of user parameters
Y (ndarray (num_movies,num_users) : matrix of user ratings of movies
R (ndarray (num_movies,num_users) : matrix, where R(i, j) = 1 if the i-th movies was rated by the j-th user
lambda_ (float): regularization parameter
Returns:
J (float) : Cost
“”"
nm, nu = Y.shape
J = 0
### START CODE HERE ###

``````for j in range(nu):
w = W[j,:]
b_j = b[0,j]
for i in range(nm):
x = X[i,:]
y = Y[i,j]
r = R[i,j]
# J += np.square(r * (np.dot(w,x) + b_j - y ) ) ## without regularization
# J += (lambda_/2) * (np.sum(np.square(W)) + np.sum(np.square(X))) ## with regularization
J = J/2

### END CODE HERE ###

return J
``````

Hi @Shagun_jain, when implementing the non-vectorized implementation of this exercise, you must add the regularization term outside the for loop. Otherwise, you would not satisfy the correctness of the given cost function.

To refactor the code, you need to fix the following line by adding the corresponding term.

``````J = J/2 + (lambda_/2) * (np.sum(np.square(W)) + np.sum(np.square(X)))
``````

I hope you find this answer useful.

Cheers,

@Enzo_Faliveni_Alzuet Thankyou for the help. Now I am able to resolve the issue .

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