比较R中的两个表，找出客户不购买的产品

我有两个表格如下：

Cust_list <- data.frame(
stringsAsFactors = FALSE,
Customer = c("Mike S.","Tim P."),
Type = c("Shoes","Socks"),
Product_ID = c(233,6546)
)


Product_Table <- data.frame(
stringsAsFactors = FALSE,
Product_ID = c(233,256,296,8536,6546,8946),
Type = c("Shoes","Shoes","Shoes", "Socks","Socks","Socks")
)

Cust_list这是否有效：

library(dplyr)
library(tidyr)
Cust_list %>% full_join(Product_Table) %>% arrange(Type) %>% 
           fill(Customer,.direction = 'down') %>% anti_join(Cust_list)
Joining, by = c("Type", "Product_ID")
Joining, by = c("Customer", "Type", "Product_ID")
  Customer  Type Product_ID
1  Mike S. Shoes        256
2  Mike S. Shoes        296
3   Tim P. Socks       8536
4   Tim P. Socks       8946

你已经试过什么了？
library(dplyr)
library(tidyr)
Cust_list %>% full_join(Product_Table) %>% arrange(Type) %>% 
           fill(Customer,.direction = 'down') %>% anti_join(Cust_list)
Joining, by = c("Type", "Product_ID")
Joining, by = c("Customer", "Type", "Product_ID")
  Customer  Type Product_ID
1  Mike S. Shoes        256
2  Mike S. Shoes        296
3   Tim P. Socks       8536
4   Tim P. Socks       8946