这是一个单元格

def compute_abs_difference_matrix(Y):n_samples = Y.shape[0]# compute the absolute difference matrix# and remember to return the matrix# INSERT YOUR CODE HEREfor i in range(n_samples):    for j in range(n_samples):        abs_difference_matrix[i, j] = abs(Y[i] - Y[j])return abs_difference_matrix

这是下一个单元格

abs_difference_matrix = compute_abs_difference_matrix(Y_pred)fig, ax = plt.subplots(figsize=(10, 10))ax.set_title("Absolute difference matrix for Y_pred")cax = ax.imshow(abs_difference_matrix)cbar = fig.colorbar(cax)

但我遇到了这个错误“name ‘abs_difference_matrix’ is not defined”，我该如何解决？我已经在上面的单元格中初始化了这个变量

回答：

你需要为abs_difference_matrix初始化一个空数组

def compute_abs_difference_matrix(Y):    abs_difference_matrix = np.array([])    n_samples = Y.shape[0]    # compute the absolute difference matrix    # and remember to return the matrix    # INSERT YOUR CODE HERE    for i in range(n_samples):        for j in range(n_samples):            abs_difference_matrix[i, j] = abs(Y[i] - Y[j])    return abs_difference_matrix