Combining pivoted rows in R by common value

Question

I have a data frame that looks like this

Name    Visit     Arrival      Departure

Jack    week 1     8:00         NA
Jack    week 1      NA          8:30
Sa         


        

Answer 1

Just aggregate it with na.omit as the aggregation function:

aggregate(dat[c("Arrival","Departure")], dat[c("Name","Visit")], FUN=na.omit)
# or
aggregate(cbind(Arrival,Departure) ~ ., data=dat, FUN=na.omit, na.action=na.pass)
#   Name Visit Arrival Departure
#1  Jack week1    8:00      8:30
#2  Adam week2    2:00      3:00
#3 Sally week5    9:00      9:30

Same logic works in data.table:

dat[, lapply(.SD,na.omit), by=.(Name,Visit)]

...or dplyr:

dat %>% group_by(Name,Visit) %>% summarise_all(na.omit)