技术：case_when使用方法

library(tidyverse)

## Error in `library()`:
## ! there is no package called 'tidyverse'

b = data_frame(a = 1:100)

## Error in `data_frame()`:
## ! could not find function "data_frame"

b %>% 
  mutate(c = case_when(
    a < 11 ~ '老大',
    a < 21 ~ '老二',
    TRUE ~ '老幺'
  )) %>% 
  .$c %>% 
  table()

## Error in `b %>% mutate(c = case_when(a < 11 ~ "老大", a < 21 ~ "老二", TRUE ~ "老幺")) %>% .$
##   c %>% table()`:
## ! could not find function "%>%"

如果我们满足了条件

and条件，是：

或命题是|，ctrl+\