大Pandas手术

Question

r = [[0,2],[2,4],[4,6],[6,8]]
i = [pd.Interval(x[0],x[1]) for x in r]
df = pd.DataFrame({"x":["a","b","a","b"],"i":i})

我正在尝试对包含间隔数据的列执行操作

^{pr2}$

但我有个错误

^{pr3}$