Question

我有两个这种格式的data.tables（实际的表各有大约一百万行）：

library(data.table)

dt1 <- data.table(
  code=c("A001", "A002","A003","A004","A005"),
  x=c(65,92,25,450,12), 
  y=c(98,506,72,76,15),
  no1=c(010101, 010156, 028756, 372576,367383),
  no2=c(876362,"",682973,78269,"")
)


dt2 <- data.table(
  code=c("A003", "A004","A005","A006","A007","A008","A009"),
  x=c(25,126,12,55,34,134,55), 
  y=c(72,76,890,568,129,675,989),
  no1=c(028756, 372576,367383,234876, 287156, 123348, 198337),
  no2=c(682973,78269,65378,"","","",789165)
)

我想将两者结合在一起，并基于所有列条目都是唯一的，仅保留唯一的行。这就是我所拥有的，但我认为有一种更好的方法可以做到：

dt3 <- rbindlist(list(dt1, dt2))
dt3 <- unique(dt3, by = c("code", "x", "y", "no1", "no2"))

一旦有了这个单一数据集，我想给任何重复的“代码”记录一些属性信息（版本号和关于该版本与先前版本的不同之处的注释）。我正在寻找的输出将是这样：

dt4 <- data.table(
  code=c("A001", "A002","A003","A004","A005", "A004","A005","A006","A007","A008","A009"),
  x=c(65,92,25,450,12,126,12,55,34,134,55), 
  y=c(98,506,72,76,15,76,890,568,129,675,989),
  no1=c(010101, 010156, 028756, 372576,367383, 372576,367383,234876, 287156, 123348, 198337),
  no2=c(876362,"",682973,78269,"",78269,65378,"","","",789165),
  version = c("V1","V1","V1","V1","V1","V2","V2","V1","V1","V1","V1"),
  unique_version=c("A001_V1", "A002_V1","A003_V1","A004_V1","A005_V1", "A004_V2","A005_V2","A006_V1","A007_V1","A008_V1","A009_V1"),
  comment = c("First_entry","First_entry","First_entry","First_entry","First_entry","New_x", "New_y_and_no2","First_entry","First_entry","First_entry","First_entry")
  )

我不确定如何实现dt4（并且考虑到实际数据集的大小将超过一百万行，这是一种有效的方式。）

修改

已将@Chase的解决方案应用于我的真实数据，我注意到我的dt3示例与获得的结果类型略有不同。这看起来更像我的真实数据：

dt6 <- data.table(
  code=c("A111", "A111","A111","A111","A111", "A111","A111","A234", "A234","A234","A234","A234", "A234","A234"),
  x=c("",126,126,"",836,843,843,126,126,"",127,836,843,843), 
  y=c("",76,76,"",456,465,465,76,76,"",77,456,465,465),
  no1=c(028756, 028756,028756,057756, 057756, 057756, 057756,028756, 028756,057756,057756, 057756, 057756, 057756),
  no2=c("","",034756,"","","",789165,"",034756,"","","","",789165)
)

comp_cols <- c("x", "y", "no1", "no2")

#grabs the names of the mismatching values and formats them how you did
f <- function(x,y) {
  n_x <- names(x)
  diff <- x != y
  paste0("New_", paste0(n_x[diff], collapse = "_and_"))
}


dt6[, version := paste0("V", 1:.N), by = code]
dt6[, unique_version := paste(code, version, sep = "_")]
dt6[, comment := ifelse(version == "V1", "First_entry", f(.SD[1], .SD[2])), by = code, .SDcols = comp_cols]

如您所见，创建注释列的建议解决方案似乎只返回第一个和第二个版本之间的第一个更改（而不是更好的V2和V3等更改）

Answer 1

这是一个解决方案-前两个很简单，评论需要多加思考：

dt5 <- copy(dt3)

comp_cols <- c("x", "y", "no1", "no2")

#grabs the names of the mismatching values and formats them how you did
f <- function(x,y) {
  n_x <- names(x)
  diff <- x != y
  paste0("New_", paste0(n_x[diff], collapse = "_and"))
}


dt5[, version := paste0("V", 1:.N), by = code]
dt5[, unique_version := paste(code, version, sep = "_")]
dt5[, comment := ifelse(version == "V1", "First_entry", f(.SD[1], .SD[2])), by = code, .SDcols = comp_cols]

最终产生这个：

> dt5
    code   x   y    no1    no2 version unique_version      comment
 1: A001  65  98  10101 876362      V1        A001_V1  First_entry
 2: A002  92 506  10156             V1        A002_V1  First_entry
 3: A003  25  72  28756 682973      V1        A003_V1  First_entry
 4: A004 450  76 372576  78269      V1        A004_V1  First_entry
 5: A005  12  15 367383             V1        A005_V1  First_entry
 6: A004 126  76 372576  78269      V2        A004_V2        New_x
 7: A005  12 890 367383  65378      V2        A005_V2 New_y_andno2
 8: A006  55 568 234876             V1        A006_V1  First_entry
 9: A007  34 129 287156             V1        A007_V1  First_entry
10: A008 134 675 123348             V1        A008_V1  First_entry
11: A009  55 989 198337 789165      V1        A009_V1  First_entry

合并来自多个data.tables的唯一行，并添加属性详细信息

1 个答案: