在R中：将具有前一行数据的行添加到数据帧 [英] In R: Add rows with data of previous row to data frame

问题描述

我有一个数据框如下所示：

  id year v1 v2 ... 
 A 1990 A 5 ... 
 A 1993 B 1 ... 
 A 1995 A 2 ... 
 A 2000 F 3 ... 
 B 1977 G 1 ... 
 B 1983 D 2 ... 
  

年变量的起始和结束值ids之间有所不同。我现在想在现有的数据框中添加行数，这些数据不包含在数据集中。这些新观察值应具有前一年的价值。数据框应该是这样的：

  id year v1 v2 ... 
 A 1990 A 5 .. 。
 A 1991 A 5 ... 
 A 1992 A 5 ... 
 A 1993 B 1 ... 
 A 1994 B 1 ... 
 A 1995 A 2 ... 
 A 1996 A 2 ... 
 A 1997 A 2 ... 
 A 1998 A 2 ... 
 A 1999 A 2 ... 
 A 2000 F 3 ... 
 B 1977 G 1 ... 
 B 1978 G 1 ... 
 B 1979 G 1 ... 
 B 1980 G 1 ... 
 B 1981 G 1 ... 
 B 1982 G 1 ... 
 B 1983 D 2 ... 
  / pre> 
 
 
非常感谢您的帮助！
解决方案
 with data.table 
  library（data.table）
 DT<  -  data.table（
 id = c（A，A，A，A，B，B），
年= ，
 v1 = c（AB，A，F，G，D），
 v2 = c（5,1,2,3,1,2）
）
 setkey（DT，id，year）
 ans<  -  DT [，list（year = seq.int年[1]，年[.N]）），by = id] 
 setkey（ans，id，year）
 DT [ans，roll = TRUE] 
  
  roll 和 rollends有很多有用的选项，请参阅？data.table  
 
I have a dataframe that looks like the following:
 id   year    v1    v2   ...
  A   1990     A     5   ...
  A   1993     B     1   ...
  A   1995     A     2   ...
  A   2000     F     3   ...
  B   1977     G     1   ...
  B   1983     D     2   ...
The starting and end values of the "year" variable differ between the ids. I would like to add rows to the existing dataframe for all years that are not included in the dataset right now. These new observations should have the values of the year before. This is how the dataframe should look like:
 id   year    v1    v2   ...
  A   1990     A     5   ...
  A   1991     A     5   ...
  A   1992     A     5   ...
  A   1993     B     1   ...
  A   1994     B     1   ...
  A   1995     A     2   ...
  A   1996     A     2   ...
  A   1997     A     2   ...
  A   1998     A     2   ...
  A   1999     A     2   ...     
  A   2000     F     3   ...
  B   1977     G     1   ...
  B   1978     G     1   ...
  B   1979     G     1   ...
  B   1980     G     1   ...
  B   1981     G     1   ...
  B   1982     G     1   ...
  B   1983     D     2   ...
Many thanks in advance for your help!
解决方案
With data.table
library(data.table)
DT <- data.table(
  id   = c("A", "A", "A", "A", "B", "B"), 
  year = c(1990, 1993, 1995, 2000, 1977, 1983), 
  v1   = c("A", "B", "A", "F", "G", "D"),
  v2   = c(5, 1, 2, 3, 1, 2)
)
setkey(DT, id, year)
ans <- DT[, list(year =  seq.int(year[1], year[.N])), by = id]
setkey(ans, id, year)
DT[ans, roll = TRUE]
There is a lot of useful options for roll and rollends, see ?data.table

                        
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