如何尽快根据组连接行

Question

我有一个如下的数据框

ClientVisitGUID LineNum TextCol
1                 1      This was a great
1                 2      report I did
2                 3      was performed today
2                 1      Another great report
2                 2      for this person
3                 2      good stuff
3                 1      I really write very
3                 3      when I put my
3                 4      mind to it

我想根据ClientVisitGUID 和行号连接行，以便获得以下输出

ClientVisitGUID TextCol
1               This was a great report I did
2               Another great report for this person was performed today
3               I really write very good stuff when I put my mind to it

我尝试了dplyr，但它需要很长时间并且无法处理我所拥有的数千行

  resultset2<-resultset %>%
    group_by(ClientVisitGUID) %>%
    arrange(LineNum) %>%
    summarize_all(paste, collapse=",")

有没有更快的方法？我对 data.table 不是很熟悉，但这很快吗？

Answer 1

第二个data.table 选项，同样使用stringi 来提高性能

library(data.table)
library(stringi)
setDT(df)
setkey(df, ClientVisitGUID, LineNum)
df1 <- df[, .(new = stri_c(TextCol, collapse = " ")), by = ClientVisitGUID]

结果

df1
#   ClientVisitGUID                                                      new
#1:               1                            This was a great report I did
#2:               2 Another great report for this person was performed today
#3:               3  I really write very good stuff when I put my mind to it

数据（感谢@ThomasIsCoding）

df <- structure(list(ClientVisitGUID = c(1L, 1L, 2L, 2L, 2L, 3L, 3L, 
3L, 3L), LineNum = c(1L, 2L, 3L, 1L, 2L, 2L, 1L, 3L, 4L), TextCol = c("This was a great", 
"report I did", "was performed today", "Another great report", 
"for this person", "good stuff", "I really write very", "when I put my", 
"mind to it")), class = "data.frame", row.names = c(NA, -9L))

Answer 2

如果你想要速度，data.table 确实是个不错的选择：

library(data.table)

setDT(resultset)
data.table::setkeyv(resultset, "ClientVisitGUID")
resultset <- resultset[order(ClientVisitGUID, LineNum)]
resultset[, .(lapply(.SD, paste, collapse = ",")), by = "ClientVisitGUID"]

一开始设置密钥需要一些时间，但之后您将获得更快的操作。设置键在连续的内存槽中重新排序属于同一组的行

示例

data = data.table("a" = c("aaa","ffff","ttt"), "b" = c(1,1,2))
data[, .(lapply(.SD, paste, collapse = ",")), by = "b"]

Answer 3

基本 R 选项使用 aggregate

result <- aggregate(TextCol~ClientVisitGUID,
                    df[order(df$ClientVisitGUID,df$LineNum),],
                    paste0, 
                    collapse = " ")

给了

> result
  ClientVisitGUID                                                  TextCol
1               1                            This was a great report I did
2               2 Another great report for this person was performed today
3               3  I really write very good stuff when I put my mind to it

数据

df <- structure(list(ClientVisitGUID = c(1L, 1L, 2L, 2L, 2L, 3L, 3L, 
3L, 3L), LineNum = c(1L, 2L, 3L, 1L, 2L, 2L, 1L, 3L, 4L), TextCol = c("This was a great", 
"report I did", "was performed today", "Another great report", 
"for this person", "good stuff", "I really write very", "when I put my", 
"mind to it")), class = "data.frame", row.names = c(NA, -9L))