pandas 将两列数据直接相加，提示警告

我想要将两列数据直接对应项相加

df['c']=df['a']+df['b']

然后提示：PerformanceWarning: DataFrame is highly fragmented. This is usually the result of calling frame.insert many times, which has poor performance. Consider joining all columns at once using pd.concat(axis=1) instead. To get a de-fragmented frame, use newframe = frame.copy()

结果是有的，但是警告看的很不舒服