r - 如何在r中合并两个具有多个相同ID的数据框

Question

我尝试合并两个 data.frames，就像代码中的那样。主要问题是我有几行具有相同的 ID，但我想将所有值(阶段)与 df1 中的 ID 合并。 我尝试搜索类似的问题，但找不到任何问题。

df1<-as.data.frame(c("a","a","a","a","a","c","c","c","b","b"))
colnames(df1)<-c("ID")
df2<-data.frame(c("a","a","a","a","a","b","b"),c(1,1,0,0,1,1,-1))
colnames(df2)<-c("ID","phase")

output<-cbind(c("a","a","a","a","a","c","c","c","b","b"),c(1,1,0,0,1,NA,NA,NA,1,-1))

我尝试使用 merge() 但它产生的 data.frame 比预期的输出大得多。而且我还丢失了应该与“c”合并的NA。

merge_out<-merge(df1,df2[,c("ID","phase")],by="ID")

ID phase
a     1
a     1
a     0
a     0
a     1
a     1
a     1
a     0
a     0
a     1
a     1
a     1
a     0
a     0
a     1
a     1
a     1
a     0
a     0
a     1
a     1
a     1
a     0
a     0
a     1
b     1
b    -1
b     1
b    -1

有什么想法吗？谢谢!

Answer 1

这有效吗:

library(dplyr)
> df1 %>% group_by(ID) %>%  mutate(uid = paste0(row_number(), ID)) %>% left_join(
+ df2%>% group_by(ID) %>% mutate(uid = paste0(row_number(), ID))
+ ) %>% select(-uid)
Joining, by = c("ID", "uid")
# A tibble: 10 x 2
# Groups:   ID [3]
   ID    phase
   <chr> <dbl>
 1 a         1
 2 a         1
 3 a         0
 4 a         0
 5 a         1
 6 c        NA
 7 c        NA
 8 c        NA
 9 b         1
10 b        -1