How to Display Categorical Groups for x-axis Label of Multiple Box plots in ggplot2-CodePudding

I am trying to examine the distribution of flights from NYC per day for each month of the year. The dataset I'm using is "nycflights13", which can be installed as a package. Then, I transform the data as follow:

# load
flights <- nycflights13::flights

# rid NA
flights <- flights %>% tidyr::drop_na(tailnum)

# filter out only flights going FROM NYC and add month
flights_with_month <- flights %>%
  filter(origin != "EWR") %>%
  mutate(mth = month(time_hour), label = TRUE)

# calculate flights per day
flights_with_month <- flights_with_month %>%
  group_by(mth, day) %>%
  mutate(total_daily_flights = n())

# making boxplots
ggplot(flights_with_month, aes(y = total_daily_flights, group = mth))  
  geom_boxplot()

This is the boxplot I'm getting; you can notice that the x-axis is not the name of the months, and it also seems that they are not ordered from January to December as well.

CodePudding user response：

Your code has two issues. mutate(mth = month(time_hour), label = TRUE) should be mutate(mth = month(time_hour, label = TRUE)), and your ggplot should set x = mth rather than grp = mth. The data were being plotted in the correct order, but with incorrect labeling.

# load
flights <- nycflights13::flights

# rid NA
flights <- flights %>% tidyr::drop_na(tailnum)

# filter out only flights going FROM NYC and add month
flights_with_month <- flights %>%
  filter(origin != "EWR") %>%
  mutate(mth = month(time_hour, label = TRUE))

# calculate flights per day
flights_with_month <- flights_with_month %>%
  group_by(mth, day) %>%
  mutate(total_daily_flights = n())

# making boxplots
ggplot(flights_with_month, aes(y = total_daily_flights, x = mth))  
  geom_boxplot()