r - 如何在R中按月重新采样？

Question

我试图找到一种在 r 中按月重新采样时间序列数据的方法。

这可以使用 Python 中的数据帧重采样来完成。有没有办法我们可以在 R 中做同样的事情？

初始数据框

     Date       Qty
05/25/2018       10
08/20/2018       15
10/15/2018       25

应改为

    Date        Qty
03/01/2018       0
04/01/2018       0
05/01/2018       10
06/01/2018       0
07/01/2018       0
08/01/2018       15
09/01/2018       0
10/01/2018       25
11/01/2018       0
12/01/2018       0

标签： r

Answer 1

data.table和lubridate接近

library( data.table )
library( lubridate )

dt <- fread("Date       Qty
05/25/2018       10
08/20/2018       15
10/15/2018       25", header = TRUE)

#create data.table with first day of each month
dt.months <- data.table( Date = seq( as.Date("2018-01-01"), length=12, by="1 month"))

#set Date as actual date, and floor to the first day of the month
dt[, Date := floor_date( as.Date( Date, format = "%m/%d/%Y"), "month" )]
#sum qty by month (noft needed in this example)

#left join
result <- dt[dt.months, on = "Date", nomatch = NA ]
#replace NA with 0
result[is.na(result)] <- 0

result
Date Qty
# 1: 2018-01-01   0
# 2: 2018-02-01   0
# 3: 2018-03-01   0
# 4: 2018-04-01   0
# 5: 2018-05-01  10
# 6: 2018-06-01   0
# 7: 2018-07-01   0
# 8: 2018-08-01  15
# 9: 2018-09-01   0
# 10: 2018-10-01  25
# 11: 2018-11-01   0
# 12: 2018-12-01   0