def plot_image_grid(image_list,
                    label_list,
                    sample_images=False,
                    num_images=6,
                    pre_title='class',
                    num_img_per_row=3,
                    cmap=None,
                    img_h_w=3):
    '''viz images from a list of images and labels
    INPUTS:
    image_list: a list of images to be plotted,
    label_list: a list of correspomding image labels'''
    


    #number of img rows
    n_row= num_images//num_img_per_row

    plt.subplots(n_row,num_img_per_row,figsize=(img_h_w*num_img_per_row,img_h_w*n_row))

    if sample_images:
    #select_random images 
        sampled_ids = random.choices(np.arange(0,len(image_list)),k=num_images)

        for i,idx in enumerate(sampled_ids):

            img = image_list[idx]
            label = label_list[i]
            plt.subplot(n_row,num_img_per_row,i+1)
            plt.title(f'{pre_title} - {label}')
            plt.axis('off')
            plt.imshow(img,cmap=cmap)
    else:
        for i,img in enumerate(image_list):

            label = label_list[i]
            plt.subplot(n_row,num_img_per_row,i+1)
            plt.title(f'{pre_title} - {label}')
            plt.axis('off')
            plt.imshow(img,cmap=cmap)

            # break the loop 
            if i==num_images-1 :
                  break 

    #show
    plt.tight_layout()
    plt.show()