rlecture

加油哇大家

library(nycflights13)
flights_planes <- full_join(flights,planes)
flights_planes <- filter(flights,str_detect(tailnum,"W"))
flights_sum <- flights_planes%>%
  filter(!is.na(engines),!is.na(seats))%>%
  group_by(engines,seats)%>%
  summarise(
    sum_d=sum(distance,na.rm=TRUE) ,
    sum_a=sum(arr_delay,na.rm=TRUE))
flights_sum2 <- flights_sum%>%group_by(engines)%>%transmute(sum_dd=sum(sum_d),sum_aa=sum(sum_a))
flights_sum2