6. Combining multiple operations with the pipe 각 도착지별로 distance 와 average delay 의 관계 살펴보기 library(tidyverse) library(nycflights13) flights by_dest = group_by(flights,dest) by_dest delay %를 이용하면 간편 delays % group_by(dest) %>% summarise( count = n(), dist = mean(distance, na.rm = TRUE), delay = mean(arr_delay, na.rm = TRUE) ) %>% filter(count > 20, dest != "HNL") - summarise : 각 그룹의 요약 통계량 계산 - co..