汇总日期和计算平均值

Question

我有一个数据框,在一列中有一长串日期,在另一列中有值,如下所示:

set.seed(1234)
df <- data.frame(date= as.Date(c('2010-09-05', '2011-09-06', '2010-09-13', 
                                 '2011-09-14', '2010-09-23', '2011-09-24',
                                 '2010-10-05', '2011-10-06', '2010-10-13', 
                                 '2011-10-14', '2010-10-23', '2011-10-24')),
                 value= rnorm(12))

我需要计算每个月每10天的平均值,但无论年份如何,都是这样:

dfNeeded <- data.frame(datePeriod=c('period.Sept0.10', 'period.Sept11.20', 'period.Sept21.30',
                                    'period.Oct0.10', 'period.Oct11.20', 'period.Oct21.31'),
                       meanValue=c(mean(df$value[c(1,2)]), 
                                   mean(df$value[c(3,4)]),
                                   mean(df$value[c(5,6)]),
                                   mean(df$value[c(7,8)]), 
                                   mean(df$value[c(9,10)]),
                                   mean(df$value[c(11,12)])))

有这么快的方法吗？

Answer 1

这是一种方法,它使用lubridate包进行月和日提取,但您可以使用基本R日期函数:

library(lubridate)
df$period <- paste(month(df$date),cut(day(df$date),breaks=c(0,10,20,31)),sep="-")
aggregate(df$value, list(period=df$period), mean)

这使 :

      period          x
1  10-(0,10] -0.5606859
2 10-(10,20] -0.7272449
3 10-(20,31] -0.7377896
4   9-(0,10] -0.4648183
5  9-(10,20] -0.6306283
6  9-(20,31]  0.4675903