为什么会出现错误"factor level [2] is duplicated"？

Question

我尝试使用 factor(month) 将月份变量（它是一个整数）转换为分类变量，但由于错误而失败了。我该如何解决？

这是我的代码：

library(tidyverse)
library(dplyr)
install.packages("nycflights13")
library(nycflights13)
month_new <- flights$month
month_new
flights %>%
   filter(dest == "HNL", air_time > 10) %>%
   factor(month_new) %>%
   ggplot(x = month_new) + geom_bar()

Answer 1

您的作业 factor(month_new) 无效。我建议mutate(month = as.factor(month))没有美学aes

library(tidyverse)
#install.packages("nycflights13")
library(nycflights13)

  flights %>%
    filter(dest == "HNL", air_time > 10) %>%
    mutate(month = as.factor(month)) %>%
    ggplot(aes(x = month)) + 
    geom_bar()

或：

library(tidyverse)
#install.packages("nycflights13")
library(nycflights13)

flights %>%
  filter(dest == "HNL", air_time > 10) 

  ggplot(flights, aes(x=factor(month)))+
    geom_bar(fill="steelblue")+
    theme_minimal()

为什么会出现错误"factor level [2] is duplicated"？

Why the error "factor level [2] is duplicated" will occur?

r

factors

data-transform