R 将逗号分隔的单元格分成行和笛卡尔积

Question

下面有 mydf 数据框。我想拆分包含逗号分隔数据的任何单元格并将其放入行中。我正在寻找类似于下面的 y 的数据框。我怎样才能通过几个步骤有效地完成它？目前我一次在一列上使用 cSplit 函数。

我尝试了cSplit(mydf, c("name","new"), ",", Direction = "long")，但是没用

library(splitstackshape)
mydf=data.frame(name = c("AB,BW","x,y,z"), AB = c('A','B'), new=c("1,2,3","4,5,6,7"))
mydf

x=cSplit(mydf, c("name"), ",", direction = "long")
x
y=cSplit(x, c("new"), ",", direction = "long")
y

Answer 1

有时 for 循环在 R 中使用完全没问题。这就是其中之一。尝试:

library(splitstackshape)
cols <- c("name", "new")
for (i in cols) {
  mydf <- cSplit(mydf, i, ",", "long")
}

mydf
##     name AB new
##  1:   AB  A   1
##  2:   AB  A   2
##  3:   AB  A   3
##  4:   BW  A   1
##  5:   BW  A   2
##  6:   BW  A   3
##  7:    x  B   4
##  8:    x  B   5
##  9:    x  B   6
## 10:    x  B   7
## 11:    y  B   4
## 12:    y  B   5
## 13:    y  B   6
## 14:    y  B   7
## 15:    z  B   4
## 16:    z  B   5
## 17:    z  B   6
## 18:    z  B   7

---

这是使用稍大的数据进行的小测试:

# concat.test = sample data from "splitstackshape"
test <- do.call(rbind, replicate(5000, concat.test, FALSE))

fun1 <- function() {
  cols <- c("Likes", "Siblings")
  for (i in cols) {
    test <- cSplit(test, i, ",", "long")
  }
  test
}

fun2 <- function() {
  test %>%
    separate_rows("Likes") %>%
    separate_rows("Siblings")
}

system.time(fun1())
#   user  system elapsed 
#  3.205   0.056   3.261 
system.time(fun2())
#   user  system elapsed 
# 11.598   0.066  11.662