我的 while 函数没有返回任何值！ 我究竟做错了什么

Question

相当新手！

我有一个看起来像这样的数据框：

currentMilestone            m2          SLA_M6          latedeliverydate            SLA_M3          earlypickupdate
            m2      2020-02-21      2020-02-18              2020-03-14          2020-02-09              2020-02-08
            m2      2020-02-21      2020-02-18              2020-02-14          2020-02-09              2020-02-08
            m2      2020-02-21      2020-02-18              2020-02-14          2020-02-09              2020-02-08
            m2      2020-02-21      2020-02-18              2020-02-14          2020-02-09              2020-02-08
            m1             NaT      2020-03-24              2020-02-14          2020-03-13              2020-03-18

我写的看起来像这样：

def flag(data):

    while data.currentMilestone== 'm1'is True:

        if data.SLA_M6  > data.latedeliverydate:
            return 'R'
        elif (data.SLA_M3 != data.earlypickupdate) & (data.latedeliverydate <= data.SLA_M6):
            return 'A'

        elif (data.SLA_M3 == data.earlypickupdate) & (data.latedeliverydate >= data.earlypickupdate):
            return 'G'
        else:
            return None

预期的输出是：

currentMilestone            m2          SLA_M6          latedeliverydate            SLA_M3          earlypickupdate         flag
            m2      2020-02-21      2020-02-18              2020-03-14          2020-02-09              2020-02-08          None    
            m2      2020-02-21      2020-02-18              2020-02-14          2020-02-09              2020-02-08          None
            m2      2020-02-21      2020-02-18              2020-02-14          2020-02-09              2020-02-08          None
            m2      2020-02-21      2020-02-18              2020-02-14          2020-02-09              2020-02-08          None
            m1             NaT      2020-03-24              2020-02-14          2020-03-13              2020-03-18            R

当我运行我的函数时，我没有任何结果......我的意思是标志不能正常工作。 所有行都设置为无

这里有什么问题？

Answer 1

为此使用numpy.select ，因为apply效率很低：

import numpy as np

cond1 = data['currentMilestone'] == 'm1'

condlist = [
    (data['SLA_M6'] > data['latedeliverydate']) & cond1,
    (data['SLA_M3'] != data['earlypickupdate']) & (data['latedeliverydate'] <= data['SLA_M6']) & cond1,
    (data['SLA_M3'] == data['earlypickupdate']) & (data['latedeliverydate'] >= data['earlypickupdate']) & cond1
]

choicelist = ['R', 'A', 'G']

data['flag'] = np.select(condlist, choicelist, default=None)

[出去]

  currentMilestone         m2     SLA_M6 latedeliverydate     SLA_M3 earlypickupdate  flag
0               m2 2020-02-21 2020-02-18       2020-03-14 2020-02-09      2020-02-08  None
1               m2 2020-02-21 2020-02-18       2020-02-14 2020-02-09      2020-02-08  None
2               m2 2020-02-21 2020-02-18       2020-02-14 2020-02-09      2020-02-08  None
3               m2 2020-02-21 2020-02-18       2020-02-14 2020-02-09      2020-02-08  None
4               m1        NaT 2020-03-24       2020-02-14 2020-03-13      2020-03-18     R