def estimate_variance(xs: np.ndarray, ys: np.ndarray, affine: np.ndarray, translation: np.ndarray, responsibility: np.ndarray) -> float: """ Estimate the variance of GMM. For simplification, we assume all the Gaussian distributions share the same variance, and each feature dimension is independent, so the variance can be represented as a scalar. :param xs: a set of points with size (N, D), N is the number of samples, D is the dimension of points :param ys: a set of points with size (M, D), M is the number of samples, D is the dimension of points :param affine: an affine matrix with size (D, D) :param translation: a translation vector with size (1, D) :param responsibility: the responsibility matrix with size (N, M) :return: the variance of each Gaussian distribution, a float """ # TODO: change the code below and compute the variance of each Gaussian return 1

To compute the variance of each Gaussian distribution, we can use the following steps:

1. Transform the xs using the affine matrix and translation vector:

   xs_transformed = xs.dot(affine) + translation

2. Compute the pairwise distance matrix between xs_transformed and ys:

   distance_matrix = np.linalg.norm(xs_transformed[:, np.newaxis, :] - ys[np.newaxis, :, :], axis=2)

3. Compute the weighted sum of squared distances for each Gaussian:

   weighted_distances = distance_matrix**2 * responsibility
   sum_weighted_distances = np.sum(weighted_distances, axis=(0, 1))

4. Compute the total weight of all the points:

   total_weight = np.sum(responsibility)

5. Compute the variance as the weighted average of the squared distances:

   variance = sum_weighted_distances / total_weight

Here's the modified code:

def estimate_variance(xs: np.ndarray, ys: np.ndarray, affine: np.ndarray,
                       translation: np.ndarray, responsibility: np.ndarray) -> float:
    """
    Estimate the variance of GMM.
    For simplification, we assume all the Gaussian distributions share the same variance,
    and each feature dimension is independent, so the variance can be represented as a scalar.

    :param xs: a set of points with size (N, D), N is the number of samples, D is the dimension of points
    :param ys: a set of points with size (M, D), M is the number of samples, D is the dimension of points
    :param affine: an affine matrix with size (D, D)
    :param translation: a translation vector with size (1, D)
    :param responsibility: the responsibility matrix with size (N, M)
    :return:
        the variance of each Gaussian distribution, a float
    """
    # Transform xs using the affine matrix and translation vector
    xs_transformed = xs.dot(affine) + translation

    # Compute the pairwise distance matrix between xs_transformed and ys
    distance_matrix = np.linalg.norm(xs_transformed[:, np.newaxis, :] - ys[np.newaxis, :, :], axis=2)

    # Compute the weighted sum of squared distances for each Gaussian
    weighted_distances = distance_matrix**2 * responsibility
    sum_weighted_distances = np.sum(weighted_distances, axis=(0, 1))

    # Compute the total weight of all the points
    total_weight = np.sum(responsibility)

    # Compute the variance as the weighted average of the squared distances
    variance = sum_weighted_distances / total_weight

    return variance