求助大佬

给定一个字符序列
shopping_list <- c("apples x4", "bag of flour",
                   "bag of sugar", "milk x2")
1. 提取苹果的数量
2. 提取买的最后一样物品和数量
3. 提取所有买的物品

1. library(tidyverse)
   
2. shopping_list <- c("apples x4", "bag of flour",
   
3.                    "bag of sugar", "milk x2")
   
4. 
   
5. shopping_use <- tbl_df(data.frame(shopping_list)) %>%
   
6.   separate(shopping_list, into = c('name', 'number'), sep = ' x') %>%
   
7.   mutate(number = ifelse(grepl('bag of', name), 1, number)) %>%
   
8.   mutate(name = gsub('bag of ', '', name))

复制代码

后面不用我写了吧？