一意の各 ID に、fruit=='apple' の first.date に基づいて、first.date の同じ列の値を与えたいと考えています。
これは私が持っているものです:
names dates fruit first.date
1 john 2010-07-01 kiwi <NA>
2 john 2010-09-01 apple 2010-09-01
3 john 2010-11-01 banana <NA>
4 john 2010-12-01 orange <NA>
5 john 2011-01-01 apple 2010-09-01
6 mary 2010-05-01 orange <NA>
7 mary 2010-07-01 apple 2010-07-01
8 mary 2010-07-01 orange <NA>
9 mary 2010-09-01 apple 2010-07-01
10 mary 2010-11-01 apple 2010-07-01
これは私が欲しいものです:
names dates fruit first.date
1 john 2010-07-01 kiwi 2010-09-01
2 john 2010-09-01 apple 2010-09-01
3 john 2010-11-01 banana 2010-09-01
4 john 2010-12-01 orange 2010-09-01
5 john 2011-01-01 apple 2010-09-01
6 mary 2010-05-01 orange 2010-07-01
7 mary 2010-07-01 apple 2010-07-01
8 mary 2010-07-01 orange 2010-07-01
9 mary 2010-09-01 apple 2010-07-01
10 mary 2010-11-01 apple 2010-07-01
これは私の悲惨な試みです：
getdates$first.date[is.na]<-getdates[getdates$first.date & getdates$fruit=='apple',]
前もって感謝します
再現可能なDF
names<-as.character(c("john", "john", "john", "john", "john", "mary", "mary","mary","mary","mary"))
dates<-as.Date(c("2010-07-01", "2010-09-01", "2010-11-01", "2010-12-01", "2011-01-01", "2010-05-01", "2010-07-01", "2010-07-01", "2010-09-01", "2010-11-01"))
fruit<-as.character(c("kiwi","apple","banana","orange","apple","orange","apple","orange", "apple", "apple"))
first.date<-as.Date(c(NA, "2010-09-01",NA,NA, "2010-09-01", NA, "2010-07-01", NA, "2010-07-01","2010-07-01"))
getdates<-data.frame(names,dates,fruit, first.date)