建立连年人物链

Question

我有一个带有 startYear、endYear 的 table，我想创建一个维度 Year 作为“startYear,endYear”

dt<- data.table(
startYear=c("1994","1995","2013"),
endYear=c("1995","2000","2021"))

我想要下面的dt table

dt<- data.table(
startYear=c("1994","1995","2013"),
endYear=c("1995","2000","2021"),
Year = c("1994,1995","1995,1996,1997,1998,1999,2000","2013,2014,2015,2016,2017,2018,2019,2020,2021")

我试试

dt$Year<- paste(seq(from = dt$startYear,
                          to = dt$endYear, by = 1))

但我收到一条错误消息

Error in seq.default(from = test$startYear, to = test$endYear, by = 1) : 
  'from' must be of length 1

我不知道如何更改它才能正常工作。谢谢

Answer 1

文字预期输出...

dt[, Year := mapply(function(a, b) paste(seq(a, b), collapse = ","), startYear, endYear) ]
#    startYear endYear                                    Year
#       <char>  <char>                                  <char>
# 1:      1994    1995                               1994,1995
# 2:      1995    2000           1995,1996,1997,1998,1999,2000
# 3:      2013    2021 2013,2014,2015,2016,2017,2018,2019,2...

但是如果您打算稍后在内部对数字进行任何操作（不仅仅是折叠的字符串），那么将 Year 作为列表列处理可能会很有用，可用于 [=13] =] 和 dplyr 本身，可能在 base R 中不那么美观，但它仍然可以在那里工作，同样，这取决于你的用例。

dt[, Year := Map(seq, startYear, endYear) ]
#    startYear endYear                              Year
#       <char>  <char>                            <list>
# 1:      1994    1995                         1994,1995
# 2:      1995    2000     1995,1996,1997,1998,1999,2000
# 3:      2013    2021 2013,2014,2015,2016,2017,2018,...

建立连年人物链

build a character chain with successive years

r

seq

data.table