dplyr :: full_join用多个“组”下降未使用的值。在y

Question

我试图保留X中的所有列，甚至它们在y中都缺少。

当我加入Y只有一个“组”时，这会起作用，并按预期添加NA条目。

但是，当我将另一个“组”添加到y值时，会默默删除。

我想念什么？

谢谢！

library(magrittr)

base <- data.frame(
  "key" = c(1,2,3,4),
  "v_a" = c("asdf","fdsa","qwert","trewq")
)

join1 <- data.frame(
"key" = c(1,2,3),
"group" = c("g_a","g_a","g_a"),
"value" = c(111,222,333)
)

join2 <- data.frame(
  "key" = c(1,2,3,4),
  "group" = c("g_b","g_b","g_b","g_b"),
  "value" = c(444,555,666,777)
)

joincombined <- dplyr::bind_rows(join1, join2)


# joining a single group retains all keys in base
# NAs are correctly assigned for missing values in "group" and "value"

res_singleJoin <- base %>% 
  dplyr::full_join(join1, by = "key")

# joining the combined df drops missing entries "group" and "value"
res_combinedJoin <- base %>% 
  dplyr::full_join(joincombined, by = "key")