“Itérer sur l'ensemble de données et calculer le vecteur moyen.” Réponses codées

Itérer sur l'ensemble de données et calculer le vecteur moyen.

In [5]:
# ===YOU SHOULD EDIT THIS FUNCTION===
def mean_naive(X):
    """Compute the mean for a dataset by iterating over the dataset
    
    Arguments
    ---------
    X: (N, D) ndarray representing the dataset.
        N is the number of samples in the dataset 
        and D is the feature dimension of the dataset
    
    Returns
    -------
    mean: (D, ) ndarray which is the mean of the dataset.
    """
    N, D = X.shape
    mean = np.zeros(D)
    # The naive approach requires us to iterate over the whole dataset with a for loop.
    for n in range(N):
        mean = mean + X[n]/N
    return mean

# ===YOU SHOULD EDIT THIS FUNCTION===
def cov_naive(X):
    """Compute the covariance for a dataset
    Arguments
    ---------
    X: (N, D) ndarray representing the dataset. 
        N is the number of samples in the dataset 
        and D is the feature dimension of the dataset
    
    Returns
    -------
    covariance: (D, D) ndarray which is the covariance matrix of the dataset.
    
    """
    N, D = X.shape
    covariance = np.zeros((D, D))
    for n in range(N):
        covariance = covariance + np.dot((X[n]-mean_naive(X)).T, (X[n]-mean_naive(X)))/N
    return covariance