定义一个频数统计函数，会使用到pd.Interval（）

pandas文档介绍：
class pandas.Interval
Immutable object implementing an Interval, a bounded slice-like interval.

Parameters：

left：orderable scalar

Left bound for the interval.

right：orderable scalar

Right bound for the interval.

closed：{‘right’, ‘left’, ‘both’, ‘neither’}, default ‘right’
# close参数控制区间的开闭，默认左开右闭

Whether the interval is closed on the left-side, right-side, both or neither. See the Notes for more detailed explanation.

Sample code:

#将一个大区间根据分组坐标分成若干个小区间，将组坐标作为元素存入列表（从小到大排序）
#list_GROUPX2 为组坐标列表，list_temp_value为数据，判断数据落入哪个小区间中，最终返回元素为各区间频数的列表
def frequency_calculate(self,list_GROUPX2,list_temp_value):
        list_zbqj = [] #组坐标区间
        for i in range(len(list_GROUPX2)):
            if i == 0:
                a = pd.Interval(left = float('-inf'), right = list_GROUPX2[i])
                list_zbqj.append(a)
            elif i == (len(list_GROUPX2)-1):
                b = pd.Interval(left = list_GROUPX2[i-1], right = float('inf'),closed = 'neither')
                list_zbqj.append(b)
            else:
                c = pd.Interval(left = list_GROUPX2[i-1], right = list_GROUPX2[i])
                list_zbqj.append(c)
        list_ps = [] #计算频数
        for i in list_zbqj:
            CNT = 0
            for j in list_temp_value:
                if j > i.left:
                    if j <= i.right:
                        CNT += 1
            list_ps.append(CNT)
        return list_ps