Update app.py

app.py

@@ -6,6 +6,7 @@ import matplotlib.pyplot as plt
 #plt.rcParams['font.sans-serif']=['SimHei']
 #plt.rcParams['axes.unicode_minus']=False
 def pd_bar():
+    pd.options.plotting.backend='matplotlib'
     plt.close('all')
     df = pd.DataFrame({'课程':['语文', '数学', '英语'], '成绩':[66, 98, 78]})
     ax = df.plot(x='课程',y='成绩',kind='bar',title='chinese word error!', color=["red","green","purple"])