R data.tableサブセットのサブセット

Question

私は顧客トランザクションデータで構成されたデータセットを持っています。特定のイベントが発生したときのタイムスタンプがあります。特定のイベントの前に起こったイベントのみを取得したいと思いますが、各顧客については、単一の時点ではありません。私は「出荷」イベントの前に起こったイベントのみを取得したいのですが

 custId   date_time_recorded    event   dateTime1 
1 280512544 2012-11-13 15:25:37.947-08   shipped 2012-11-13 15:25:37 
2 280512544 2012-11-13 15:22:42.614-08  statusCheck 2012-11-13 15:22:42 
3 280512544 2012-11-13 15:03:16.62-08  statusCheck 2012-11-13 15:03:16 
4 280512544 2012-11-13 15:01:35.149-08  statusCheck 2012-11-13 15:01:35 
5 280512544 2012-11-13 14:45:41.964-08  status-picked 2012-11-13 14:45:41 
6 280512544 2012-11-13 14:44:57.664-08 warehouse_notified 2012-11-13 14:44:57 
7 280512544 2012-11-13 14:44:57.644-08  statusCheck 2012-11-13 14:44:57 
8 280512544 2012-11-13 13:05:15.725-08  recordCreated 2012-11-13 13:05:15 
9 280510610 2012-11-13 09:22:36.427-08   shipped 2012-11-13 09:22:36 
10 280510610 2012-11-13 09:20:07.202-08  statusCheck 2012-11-13 09:20:07 
11 280510610 2012-11-13 09:14:56.182-08  statusCheck 2012-11-13 09:14:56 

：

は、ここでのスナップショットです。私は現在、これを達成するためにddplyを使用していますが、時間がかかります。

keepPreShip <- function(x){ 
shipTime <- fastPOSIXct(x[grep("shipped", x$event, ignore.case = T), "date_time_recorded"],tz = "UTC") 
#shipTime <- fastPOSIXct(x[x$event =="shipped", "date_time_recorded"],tz = "UTC") 
x <- x[x$dateTime1 < shipTime,] 
} 

system.time(eventsMain1 <- ddply(ss1, .(custId), keepPreShip)) 

これを行う方法はありますか？たぶんdata.tableと？

は、ここでデータのdputです：

> dput(ss1) 
structure(list(custId = c(280512544L, 280512544L, 280512544L, 
280512544L, 280512544L, 280512544L, 280512544L, 280512544L, 280510610L, 
280510610L, 280510610L, 280510610L, 280510610L, 280510610L, 280510610L, 
280510610L, 280511123L, 280511123L, 280511123L, 280511123L), 
    date_time_recorded = c("2012-11-13 15:25:37.947-08", "2012-11-13 15:22:42.614-08", 
    "2012-11-13 15:03:16.62-08", "2012-11-13 15:01:35.149-08", 
    "2012-11-13 14:45:41.964-08", "2012-11-13 14:44:57.664-08", 
    "2012-11-13 14:44:57.644-08", "2012-11-13 13:05:15.725-08", 
    "2012-11-13 09:22:36.427-08", "2012-11-13 09:20:07.202-08", 
    "2012-11-13 09:14:56.182-08", "2012-11-13 09:11:40.438-08", 
    "2012-11-13 09:03:51.571-08", "2012-11-13 09:03:51.461-08", 
    "2012-11-13 09:03:49.174-08", "2012-11-13 06:42:10.208-08", 
    "2012-11-13 13:51:05.039-08", "2012-11-13 13:13:16.452-08", 
    "2012-11-13 12:42:08.917-08", "2012-11-13 12:28:51.541-08" 
    ), event = c("shipped", "statusCheck", "statusCheck", "statusCheck", 
    "status-picked", "warehouse_notified", "statusCheck", "recordCreated", 
    "shipped", "statusCheck", "statusCheck", "statusCheck", "status-picked", 
    "warehouse_notified", "statusCheck", "recordCreated", "shipped", 
    "statusCheck", "statusCheck", "statusCheck"), dateTime1 = structure(c(1352820337.947, 
    1352820162.614, 1352818996.62, 1352818895.149, 1352817941.964, 
    1352817897.664, 1352817897.644, 1352811915.725, 1352798556.427, 
    1352798407.202, 1352798096.182, 1352797900.438, 1352797431.571, 
    1352797431.461, 1352797429.174, 1352788930.208, 1352814665.039, 
    1352812396.452, 1352810528.917, 1352809731.541), class = c("POSIXct", 
    "POSIXt"), tzone = "UTC")), .Names = c("custId", "date_time_recorded", 
"event", "dateTime1"), row.names = c(NA, 20L), class = "data.frame") 

Answer 1

これは動作します。私はより速くそれを望む。

require(data.table) 
# convert this column to date format first 
ss1$date_time_recorded <- as.POSIXct(ss1$date_time_recorded) 
dt <- data.table(ss1, key="custId") 
dt[, .SD[dateTime1 < date_time_recorded[event == "shipped"]], by=custId] 

#  custId date_time_recorded   event   dateTime1 
# 1: 280510610 2012-11-13 06:42:10 recordCreated 2012-11-13 06:42:10 
# 2: 280511123 2012-11-13 12:42:08 statusCheck 2012-11-13 12:42:08 
# 3: 280511123 2012-11-13 12:28:51 statusCheck 2012-11-13 12:28:51 
# 4: 280512544 2012-11-13 13:05:15 recordCreated 2012-11-13 13:05:15