如何解决计算data.table中每个月的股票数量不同的平均每月回报
假设我有一个data.table,priceDT,每天观察多个股票的回报,如下所示:
> priceDT
Date Return Share
1: 2011-01-03 0.04500000 GAI
2: 2011-01-03 -0.02100000 KDV
3: 2011-01-04 0.03300000 GAI
4: 2011-01-04 0.01770000 KDV
5: 2011-01-05 -0.01742000 GAI
6: 2011-01-05 0.07900000 KDV
7: 2011-02-06 0.02400000 GAI
8: 2011-02-06 -0.02110000 KDV
9: 2011-02-07 -0.04300000 AFT
10: 2011-02-07 0.01199700 AIP
11: 2011-02-07 0.00551810 ARH
12: 2011-02-07 0.07451101 BIK
13: 2011-02-07 -0.03495597 BLU
14: 2011-02-07 -0.06062462 CGR
15: 2011-02-07 -0.03660000 GAI
16: 2011-02-07 -0.01240000 KDV
我想计算给定月份所有股票的平均月收益。因此,在2011年1月,这两个股票的平均回报率。由于“份额”列,我们知道它只有两个份额。第一步是获取该月每股的平均回报。然后获得该月股票投资组合的平均回报。因此,在一月份,GAI的平均值为0.02019333,KDV的平均值为0.02523333。因此,该月的平均值是:0.02019333
这就是投资组合收益的逻辑。我想在接下来的几个月中在data.table中重复
对于我的示例数据,我想要这样的结果:
portfolio
Date avg_return
1: 2011-01 0.02271333
2: 2011-02 -0.008700561
数据:
priceDT <- fread(text = "Date,Return,Share
2011-01-03,0.045,GAI
2011-01-03,-0.021,KDV
2011-01-04,0.033,GAI
2011-01-04,0.0177,KDV
2011-01-05,-0.01742,GAI
2011-01-05,0.079,KDV
2011-02-06,0.024,GAI
2011-02-06,-0.0211,KDV
2011-02-07,-0.043,AFT
2011-02-07,0.011997,AIP
2011-02-07,0.0055181,ARH
2011-02-07,0.074511006,BIK
2011-02-07,-0.034955973,BLU
2011-02-07,-0.060624622,CGR
2011-02-07,-0.0366,GAI
2011-02-07,-0.0124,KDV
")
portfolio <- fread(text = "Date,avg_return
2011-01,0.022713333
2011-02,-0.01194431
")
解决方法
这是另一种方法,尽管我的结果与您的结果不符。
您可以为分组结果创建“年-月”列。按照您的步骤,您可以计算每个月(每个份额)的平均份额,我们将其称为ShareMean
。
然后,您可以计算给定月份所有份额中这些平均值的平均值,我们将其称为MonthMean
。
这是您的主意吗?
library(data.table)
priceDT[,YearMonth := list(substr(Date,1,7))]
priceDT[,.(ShareMean = mean(Return)),by = c("YearMonth","Share")][,.(MonthMean = mean(ShareMean)),by = "YearMonth"]
输出
YearMonth MonthMean
1: 2011-01 0.022713333
2: 2011-02 -0.008700561
,
您可以直接计算每月收益,我会这样做:
library(tidyverse)
library(lubridate)
priceDT %>%
mutate(month = month.abb[month(Date)]) %>%
group_by(month) %>%
summarise(avg_return = mean(Return))
({month.abb[month(Date)]
表示月份的缩写,例如1月,2月)
或首先计算给定月份的平均份额:
priceDT %>%
mutate(month = month.abb[month(Date)]) %>%
group_by(month,Share) %>%
summarise(avg_return = mean(Return))
然后您可以按照上面的方法计算平均每月收益。
,priceDT[,mean(Return),by = .(ym = format(Date,"%Y-%m"),Share)
][,mean(V1),by = ym]
# ym V1
# 1: 2011-01 0.022713333
# 2: 2011-02 -0.008700561
,
我看不出您如何执行步骤t,才能获得所有共享股票的每月平均回报...。 但这也许会让您入门?
#make dates
priceDT[,Date := as.Date( Date ) ]
# step 1: mean by share by month
priceDT[,.(avg_return = mean( Return,na.rm = TRUE) ),by = .( month = format(Date,Share ) ]
但是在这里,我看不到提供portfolio
的逻辑...
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