Python中向现有数据帧追加重影行的优化算法
我有一个数据帧,我想将重影行(现有行的副本)附加到数据帧Python中向现有数据帧追加重影行的优化算法,python,algorithm,pandas,dataframe,Python,Algorithm,Pandas,Dataframe,我有一个数据帧,我想将重影行(现有行的副本)附加到数据帧 id month as_of_date1 turn age 119 5712 201401 2014-01-01 9 0 120 5712 201402 2014-02-01 9 1 121 5712 201403 2014-03-01 9 2 122 5712 201404 2014-04-01 9 3 123 5712 201405 2014-05
id month as_of_date1 turn age
119 5712 201401 2014-01-01 9 0
120 5712 201402 2014-02-01 9 1
121 5712 201403 2014-03-01 9 2
122 5712 201404 2014-04-01 9 3
123 5712 201405 2014-05-01 9 4
124 5712 201406 2014-06-01 9 5
125 9130 201401 2014-01-01 9 0
126 9130 201402 2014-02-01 9 1
127 9130 201403 2014-03-01 9 2
128 9130 201404 2014-04-01 9 3
129 9130 201405 2014-05-01 9 4
重影行由以下条件选择:
如果age小于turn,我们需要追加最新的行,直到age==turn of
或作为\u of_date1==now()
现在我正在使用下面的代码,但是由于数据很大,大约有200000行,有100个字段,所以它永远需要
tdf1=tdf.loc[(tdf['age']<tdf['turn'])]
tdf2=tdf1.drop_duplicates(subset=['id'],keep='last')
leads=tdf2.index.tolist()
for lead in leads:
ttdf=tdf.loc[[lead]]
diff1 = relativedelta.relativedelta(datetime.datetime(2018,6,1),tdf.loc[lead,'as_of_date1']).months
diff2=tdf.loc[lead,'turn']-tdf.loc[lead,'age']
diff=min(diff1,diff2)
for i in range(0,diff):
tdf = tdf.append(ttdf, ignore_index=True)
如果有人知道一个更快的算法,,我将不胜感激,因为@Parfit在附加到数据帧的注释中提到了这个算法,它确实会消耗内存,在循环中执行它根本不被建议。所以我用了下面的方法,难以置信地提高了速度
a=[]
for lead in leads:
ttdf=tdf.loc[[lead]]
diff1 = relativedelta.relativedelta(datetime.datetime(2018,6,1),tdf.loc[lead,'as_of_date1']).months
diff2=tdf.loc[lead,'turn']-tdf.loc[lead,'age']
diff=min(diff1,diff2)
for i in range(0,diff):
a.append(ttdf)
tdf = tdf.append(a, ignore_index=True)
你能包括你的预期产出吗?我认为,在您的示例中,在循环中,您可以在中间数组中附加ttdf,然后使用类似于np.concatenate的东西。它会更快。
a=[]
for lead in leads:
ttdf=tdf.loc[[lead]]
diff1 = relativedelta.relativedelta(datetime.datetime(2018,6,1),tdf.loc[lead,'as_of_date1']).months
diff2=tdf.loc[lead,'turn']-tdf.loc[lead,'age']
diff=min(diff1,diff2)
for i in range(0,diff):
a.append(ttdf)
tdf = tdf.append(a, ignore_index=True)