在使用Python绘制条形图时忽略Figsize参数

下面的代码生成嵌入的绘图，但由于我不理解的原因，定义绘图大小（figsize）的参数显然被忽略

plt.figure(figsize=(15, 15))

ax = SP500_Growth_quantiles.plot(kind = 'bar')
ax.set_title('Quantiles of the Probability Distribution of S&P 500 Growth in 2018')
ax.set(ylabel = 'S&P 500 Growth in 2018', xlabel = 'Quantile')

图片：

你是说

fig, ax = plt.subplots(figsize=(15, 15))
SP500_Growth_quantiles.plot(kind = 'bar', ax=ax)
ax.set_title('Quantiles of the Probability Distribution of S&P 500 Growth in 2018')
ax.set(ylabel = 'S&P 500 Growth in 2018', xlabel = 'Quantile')