结合case\u when和mutate的条件语句

我想创建一个绘制两个变量的双变量地图: production 和 possession . 为了给部分数据提供正确的颜色,我想添加一列颜色代码 "A", "B", "C" 对于一个变量和另一个变量 1, 2, 3 . 然后将两者结合起来。只需按照以下示例对数据进行编码即可:

下面是我的示例df和失败代码:

library(dplyr)

example_df <- structure(list(production = c(0.74, 1.34, 2.5), possession = c(5, 
23.8, 124.89)), .Names = c("production", "possession"), row.names = c(NA, 
-3L), class = c("tbl_df", "tbl", "data.frame"))

example_df %>%
  mutate(colour_class_nr = case_when(.$production %in% 0.068:0.608 ~ "1",
                                     .$production %in% 0.609:1.502 ~ "2",
                                     .$production %in% 1.503:3.061 ~ "3",
                                     TRUE ~ "none"),
         colour_class_letter = case_when(.$possession %in% 0.276:9.6 ~ "A",
                                         .$possession %in% 9.7:52 ~ "B",
                                         .$possession %in% 52.1:155.3 ~ "C",
                                         TRUE ~ "none"))

根据这些结果…:

# A tibble: 3 x 4
  production possession colour_class_nr colour_class_letter
       <dbl>      <dbl> <chr>           <chr>              
1      0.740       5.00 4               none               
2      1.34       23.8  4               none               
3      2.50      125    4               none  

但这是期望的输出:

# A tibble: 3 x 4
  production possession colour_class_nr colour_class_letter
       <dbl>      <dbl>           <dbl> <chr>              
1      0.740       5.00 2                A               
2      1.34       23.8  2                B               
3      2.50      125    3                C 

我是新来的 case_when() 结合mutate,希望有人能帮忙。