r - 将日期范围拆分为几个以 YYYY-12-31 结尾的 block

Question

df <- data.frame(group = c("a", "a", "b", "b"),
                 start = c("2017-05-01", "2019-04-03", "2011-03-03", "2014-05-07"),
                 end = c("2018-09-01", "2020-04-03", "2012-05-03", "2016-04-02"))  

假设我有以下 df:

  group      start        end
1     a 2017-05-01 2018-09-01
2     a 2019-04-03 2020-04-03
3     b 2011-03-03 2012-05-03
4     b 2014-05-07 2016-04-02

我想把它变成这种格式，每条记录分成开始日期和那年和随后几年的 31/12:

  group      start        end
1     a 2017-05-01 2017-12-31
2     a 2018-01-01 2018-09-01
3     a 2019-04-03 2019-12-31
4     a 2020-01-01 2020-04-03
5     b 2011-03-03 2011-12-31
6     b 2012-01-01 2012-05-03
7     b 2014-05-07 2014-12-31
8     b 2015-01-01 2015-12-31
9     b 2016-01-01 2016-04-02

关于如何解决这个问题的任何想法？

编辑:

我主要关注的不是同一年内的日期范围。但是，正如 chinsoon12 指出的那样，如果该方法也可以处理它们，确实会有所帮助，例如在此数据集中:

df <- data.frame(group = c("a", "a", "b", "b", "c"),
                 start = c("2017-05-01", "2019-04-03", "2011-03-03", "2014-05-07", "2017-02-01"),
                 end = c("2018-09-01", "2020-04-03", "2012-05-03", "2016-04-02", "2017-04-05")) 

最终结果将保留最后一行:

   group      start        end
1      a 2017-05-01 2017-12-31
2      a 2018-01-01 2018-09-01
3      a 2019-04-03 2019-12-31
4      a 2020-01-01 2020-04-03
5      b 2011-03-03 2011-12-31
6      b 2012-01-01 2012-05-03
7      b 2014-05-07 2014-12-31
8      b 2015-01-01 2015-12-31
9      b 2016-01-01 2016-04-02
10     c 2017-02-01 2017-04-05  

Answer 1

一个可能的解决方案 data.table :

library(data.table)
setDT(df)

df[df[, rep(.I, 1 + year(end) - year(start))]
   ][, `:=` (start = pmax(start[1], as.Date(paste0(year(start[1]) + 0:(.N-1), '-01-01'))),
             end = pmin(end[.N], as.Date(paste0(year(end[.N]) - (.N-1):0, '-12-31'))))
     , by = .(group, rleid(start))][]

这使:

    group      start        end
 1:     a 2017-05-01 2017-12-31
 2:     a 2018-01-01 2018-09-01
 3:     a 2019-04-03 2019-12-31
 4:     a 2020-01-01 2020-04-03
 5:     b 2011-03-03 2011-12-31
 6:     b 2012-01-01 2012-05-03
 7:     b 2014-05-07 2014-12-31
 8:     b 2015-01-01 2015-12-31
 9:     b 2016-01-01 2016-04-02
10:     c 2017-02-01 2017-04-05

两个替代解决方案 data.table :

# alternative 1:
df[, ri := rowid(group)
   ][df[, rep(.I, 1 + year(end) - year(start))]
     ][, `:=` (start = if (.N == 1) start else c(start[1], as.Date(paste0(year(start[1]) + 1:(.N-1), '-01-01') )),
               end = if (.N == 1) end else c(as.Date(paste0(year(end[.N]) - (.N-1):1, '-12-31') ), end[.N]))
       , by = .(group, ri)][, ri := NULL][]

# alternative 2:
df[, ri := rowid(group)
   ][df[, rep(.I, 1 + year(end) - year(start))]
     ][, `:=` (start = pmax(start[1], as.Date(paste0(year(start[1]) + 0:(.N-1), '-01-01'))),
               end = pmin(end[.N], as.Date(paste0(year(end[.N]) - (.N-1):0, '-12-31'))))
       , by = .(group, ri)][, ri := NULL][]

使用数据:

df <- data.frame(group = c("a", "a", "b", "b", "c"),
                 start = c("2017-05-01", "2019-04-03", "2011-03-03", "2014-05-07", "2017-02-01"),
                 end = c("2018-09-01", "2020-04-03", "2012-05-03", "2016-04-02", "2017-04-05")) 
df[2:3] <- lapply(df[2:3], as.Date)