R 基于条件创建二元成对数据集

我有一个一元数据集，看起来像这样：

df<-structure(list(Number = c("375_1", "375_1", "375_1", "375_1", 
"375_1", "375_1", "375_1", "375_1", "647_1", "647_1", "647_1", 
"647_1", "647_1", "647_1", "647_1", "647_1", "647_1", "647_1", 
"647_1", "647_1"), year = c(1973, 1973, 1973, 1973, 1973, 1973, 
1973, 1973, 1981, 1981, 1981, 1981, 1981, 1981, 1981, 1981, 1981, 
1981, 1981, 1981), Country = c("AUT", "PRT", "CHE", "NOR", "SWE", 
"ISL", "DNK", "GBR", "BRA", "CHL", "EGY", "IND", "ISR", "MEX", 
"PER", "KOR", "PAK", "PHL", "TUN", "TUR")), row.names = c(NA, 
-20L), class = c("tbl_df", "tbl", "data.frame"))

final <- data.frame(Number = c("375_1", "375_1", "375_1", "375_1", "375_1", "375_1", "375_1","375_1", "375_1", "375_1", "375_1","375_1"), 
                    year = c(1973, 1973, 1973, 1973, 1973, 1973, 1973, 1973,1973, 1973, 1973, 1973), 
                    Country1 = c("AUT", "AUT", "AUT", "AUT", "AUT", "AUT", "AUT","PRT","PRT","PRT","PRT","PRT"), 
                    Country2 = c("PRT", "CHE", "NOR", "SWE", "ISL", "DNK", "GBR","CHE","NOR","SWE", "ISL","DNK"),
                    stringsAsFactors = FALSE)     

在集团内的每一个国家继续这样做。 我想找到一种简洁明了的方法来做到这一点

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非常感谢您的帮助

以供将来参考，我认为解决方案如下

final <- df %>% group_by(Number, year)%>%  expand(Country1 = Country, Country2= Country) %>% filter(Country1!=Country2)

final%groupby（Number，year）%%>%expand（Country1=Country，Country2=Country）%%>%filter（Country1！=Country2）

使用

tidyverse

：

library(tidyverse)

df %>%
  full_join(df, by=c("Number", "year")) %>%
  filter(Country.x != Country.y)

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final

数据帧提供了最终输出的大致外观。因为我必须手工写，写所有的东西都要花很长时间。我想可以考虑<代码>最终< /COD>数据帧作为输出的<代码>头（）>代码>。这意味着在实际输出中，我希望变量的每个值都有

Number

所有可能的二元组合。处理这个问题有什么想法吗？