这段代码发生了什么错误，我不明白

Question

plt.figure(figsize=(12, 12))

for i, class_name in enumerate(classes.values()):
    
    class_subset = raw_data.loc[raw_data.class_name == class_name].sample(n=4)
    
    img_names = class_subset.filename.to_list()
    
    for j, img in enumerate(img_names):
        image = cv2.imread(os.path.join(img_dir, img))
        
        ## convert image to RGB
        image_rgb = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
        
        ## subplot variables - (# of rows, # of columns, iterate through locations on grid)
        plt.subplot(8, 4, 4 * i + j + 1)
        plt.imshow(image_rgb, aspect=1)
        
        ## label with filename and diagnosis
        plt.xlabel('{}'.format(class_name))

        plt.tight_layout() 

有人定义错误并解码此代码。

Answer 1

该错误表明变量“classes”（您试图在第 3 行中枚举）不存在。