每当持续时间少于11秒时，我尝试将数据帧M附加到空数据帧Linked_df上。 以下代码附加了一个数据框：
Linked_df=pd.DataFrame()
Linked=pd.DataFrame()
#for each unique date
for unq_date in Unique_Dates:
#obtain dataframe of Mi and Ri of a specific date
#add a column for index to track orignal index
M=Mi.loc[(pd.to_datetime(Mi['EventDate']) == unq_date) ]
R=Ri.loc[(pd.to_datetime(Ri['EventDate']) == unq_date) ]
#Check if unique date exist in M
Linked_df = R.apply(lambda row: create_dur(row['start_DateTime'], M,Linked_df), axis=1)
Linked=Linked.append(Linked_df,ignore_index=True)
该函数调用并将M附加到数据帧Linked_df中：
def create_dur(row,M,Linked_df):
M['duration']=(M['Event Read Time'] - row).dt.total_seconds()
M.loc[M.duration < 0, 'duration'] = (row-M['Event Read Time']).dt.total_seconds()
M=M.loc[M.duration < 11]
#print(M['duration'])
#print(M)
row1 = pd.DataFrame(M)
#Linked_df=pd.concat([Linked_df, row1], ignore_index=True)
Linked_df=Linked_df.append(M,ignore_index=True)
print(Linked_df)
return Linked_df
函数的输出：
EventDate Id_str EventTime Event Read Time lat \
0 2017-11-09 72057594042646832 01:13:24 2017-11-09 01:13:24 -27.73409
1 2017-11-09 72057594042646832 01:13:29 2017-11-09 01:13:29 -27.73200
2 2017-11-09 72057594042646848 01:13:30 2017-11-09 01:13:30 -27.73192
3 2017-11-09 72057594042646864 01:13:32 2017-11-09 01:13:32 -27.73399
4 2017-11-09 72057594042646880 01:13:33 2017-11-09 01:13:33 -27.73398
long Speed Sprung Weight Frame Torque ind_val_Mi duration
0 22.96531 9.0 468.0 88.0 101995 6.0
1 22.97351 36.0 280.0 -4.0 101996 1.0
2 22.97347 36.0 270.0 -10.0 101997 0.0
3 22.96537 0.0 480.0 85.0 101998 2.0
4 22.96537 2.0 489.0 89.0 101999 3.0
EventDate Id_str EventTime Event Read Time lat \
0 2017-11-09 72057594042646832 01:13:29 2017-11-09 01:13:29 -27.73200
1 2017-11-09 72057594042646848 01:13:30 2017-11-09 01:13:30 -27.73192
2 2017-11-09 72057594042646864 01:13:32 2017-11-09 01:13:32 -27.73399
3 2017-11-09 72057594042646880 01:13:33 2017-11-09 01:13:33 -27.73398
结果未添加到空白数据框中。似乎正在更新数据框。是什么原因？我尝试了concat但得到一个空列表。