将匹配列从长转换为宽

# merge the data
m = merge(df.1, df.2)

# convert it to wide
library(data.table)
dcast(m, ID + B ~ C, value.var = "C")
#       ID B    N    S    W
# 1   6007 M    N    S <NA>
# 2 123456 F <NA>    S <NA>
# 3 987654 F <NA> <NA>    W

我让你把这些列重命名为C1,C2。。。,如果你真的想。

使用此数据:

df.1 = read.table(text = "ID     B 
006007 M
123456 F
987654 F", stringsAsFactors = FALSE, header = T)

df.2 = read.table(text = "ID     B C
006007 M N
006007 M S
123456 F S
987654 F W", stringsAsFactors = FALSE, header = T)