dplyr使用组内选择功能进行变异

在分组后，我试图在dplyr中的mutate函数中使用select函数

df <- data.frame(city = c(rep(1,4),rep(2,4)), 
            year = rep(1,8),
            victory = rep(c(1,0,0,0),2),
            affiliation = c("a","b","c","d","e","f","g","h"))

期望：

group_affiliation = c(rep("a",4), rep("e",4)

对于每个城市，年份组，我试图获取由victory==1定义的条目的从属关系值，然后变异为整个组

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另外，我本可以分两部分来做，重新合并组，但我的计算机无法处理向量大小

我花了太多时间在这上面，我离得太近了。谢谢。

library(dplyr)      
df %>% 
   group_by(city,year) %>% 
   mutate(group_affiliation = affiliation[victory==1])

library(dplyr)      
df %>% 
   group_by(city,year) %>% 
   mutate(group_affiliation = affiliation[victory==1])