正如@henry ecker所评论的，您应该迭代ax.patches。pandas plot函数返回的是轴，而不是面片/矩形。

df = pd.DataFrame({
    'coast': np.random.choice(['Cat1','Cat2'], size=20000, p=[0.9, 0.1])
})

def code(c):
    plt.rc('figure', figsize=(10, 5))

    ax = c.value_counts().plot(kind='bar')

    for value in ax.patches:
        height = value.get_height()
        plt.text(value.get_x() + value.get_width()/2., 
                 1.002*height,'%d' % int(height), ha='center', va='bottom')

code(df.coast)

或者，只需绘制图并获得自己的值计数。条形图的x轴只是一个0到条数的数组（本例中为2）。

df = pd.DataFrame({
    'coast': np.random.choice(['Cat1','Cat2'], size=20000, p=[0.9, 0.1])
})

def code(c):
    plt.rc('figure', figsize=(10, 5))
    counts = c.value_counts()    
    ax = counts.plot(kind='bar')

    for i in range(len(counts)):
        ax.text(
            x = i,
            y = counts[i] + 600,
            s = str(counts[i]),
            ha = 'center', fontsize = 14
        )
    ax.set_ylim(0,25000)

code(df.coast)