Rstudio

library(tidyverse) library(nycflights13) flights

#### 1. What is the average and standard deviation of arrival delay for each carrier? Among three major US airlines (UA, AA, DL), which one is the best and which one is the worst in terms of delay? ```{r} flight1<- flights %>% group_by(flights, dest) %>% # set group structure for each carrier summarise(avg.arr.delay= , sd.arr.delay= ) # calculate average and standard deviation

flight1 %>% filter(flights, carrier%in%c("UA","AA","DL")) %>% # filter three airlines arrange(flights, dep_delay, desc(day)) # sort ```

#### 2. For each of the three major US airlines, how many flights have been canceled? Draw a bar chart to show your result, and label each bar with the numbers. ```{r} flights %>% filter( flights, carrier%in%c("UA","AA","DL") ) %>% # filter three airlines, and canceled flights group_by(flights$) %>% # set group structure for each carrier summarise(count= ) %>% # what is the function to get count ggplot(aes(x= , y= )) + # specify x and y on your bar chart geom_bar(stat="identity", fill="blue") + geom_text(stat="identity", aes(label=count), vjust=-0.5)