I have two data frames:
我有两个数据框：
dput (df1)
structure(list(ID = c(1, 2, 3, 4, 5), Age = c(29, 40, 60, 30,
39), BMI = c(27, 26, 31, 33, 26), A.1 = c(1L, 0L, 1L, 1L, 0L),
A.2 = c(0L, 0L, 0L, 0L, 0L), A.3 = c(0L, 1L, 0L, 0L, 1L),
A.4 = c(0L, 1L, 0L, 0L, 1L), B.1 = c(1L, 1L, 1L, 0L, 0L),
B.2 = c(1L, 1L, 1L, 1L, 1L), B.3 = c(1L, 0L, 1L, 0L, 0L),
B.4 = c(1L, 1L, 0L, 1L, 1L)), .Names = c("ID", "Age", "BMI",
"A.1", "A.2", "A.3", "A.4", "B.1", "B.2", "B.3", "B.4"), row.names = c(NA,
5L), class = "data.frame")
df1
ID Age BMI A.1 A.2 A.3 A.4 B.1 B.2 B.3 B.4
1 1 29 27 1 0 0 0 1 1 1 1
2 2 40 26 0 0 1 1 1 1 0 1
3 3 60 31 1 0 0 0 1 1 1 0
4 4 30 33 1 0 0 0 0 1 0 1
5 5 39 26 0 0 1 1 0 1 0 1
dput (df2)
structure(list(ID = c(1, 2, 3, 4, 5), outcome = c(NA, NA, 2,
NA, NA)), .Names = c("ID", "outcome"), row.names = c(NA, -5L), class = "data.frame")
df2
ID outcome
1 1 NA
2 2 NA
3 3 2
4 4 NA
5 5 NA
dput 
