r - 使用不同的数据框填充列中的缺失值

Question

我有一个示例数据框，其中有一列每行存储 3 个字母。数据框还有 2 个附加列:日期和颜色:

Alphabet       Date   Colour
  ABC    2018-09-10   green
  DEF    2017-06-11   red
  GHI    2016-05-12   blue
  JKL            NA   yellow
  MNO            NA   orange
  PQR       Unknown   brown

此数据框中的某些日期丢失/未知。我有另一个数据框，它也有字母表和日期列。第二个数据帧包含第一个数据帧中缺失日期的日期:

Alphabet       Date   
  JKL    2017-06-07  
  MNO    2018-08-03   
  PQR    2019-10-07
  STU    2019-11-08
  VWX    2019-12-08   

我想通过匹配两个数据帧中的字母记录来填充第一个数据帧中缺失的日期，然后将第二个数据帧中的日期插入到第一个数据帧中。

期望的输出:

Alphabet       Date   Colour
  ABC    2018-09-10   green
  DEF    2017-06-11   red
  GHI    2016-05-12   blue
  JKL    2017-06-07   yellow
  MNO    2018-08-03   orange
  PQR    2019-10-07   brown

感谢任何帮助。

Answer 1

一个选项是与data.table连接

library(data.table)
setDT(df1)[df2, Date := i.Date, on = .(Alphabet)]
df1
#   Alphabet       Date Colour
#1:      ABC 2018-09-10  green
#2:      DEF 2017-06-11    red
#3:      GHI 2016-05-12   blue
#4:      JKL 2017-06-07 yellow
#5:      MNO 2018-08-03 orange
#6:      PQR 2019-10-07  brown

更新

使用新的“df2n”数据集

i1 <- is.na(df1$Date)|df1$Date %in% "Unknown"
setDT(df1)[df2n[df2n$Alphabet %in% df1$Alphabet[i1],],
         Date := i.Date, on = .(Alphabet)]
df1
#   Alphabet       Date Colour
#1:      ABC 2018-09-10  green
#2:      DEF 2017-06-11    red
#3:      GHI 2016-05-12   blue
#4:      JKL 2017-06-07 yellow
#5:      MNO 2018-08-03 orange
#6:      PQR 2019-10-07  brown

---

或者使用base R中的match

i1 <- match(df2$Alphabet, df1$Alphabet)
df1$Date[i1] <- df2$Date

数据

df1 <- structure(list(Alphabet = c("ABC", "DEF", "GHI", "JKL", "MNO", 
"PQR"), Date = c("2018-09-10", "2017-06-11", "2016-05-12", NA, 
NA, "Unknown"), Colour = c("green", "red", "blue", "yellow", 
"orange", "brown")), class = "data.frame", row.names = c(NA, 
-6L))

df2 <- structure(list(Alphabet = c("JKL", "MNO", "PQR"), Date = c("2017-06-07", 
"2018-08-03", "2019-10-07")), class = "data.frame", row.names = c(NA, 
-3L))

df2a  <- structure(list(Alphabet = c("JKL", "MNO", "PQR", "STU", "VWX"
), Date = c("2017-06-07", "2018-08-03", "2019-10-07", "2019-11-08", 
"2019-12-08")), class = "data.frame", row.names = c(NA, -5L))