data.frame中的unique/sort

Question

我有一个这样的数据框:

x=c("01","01","01","22","22","03","03","03","35","35")
y=c("f","f","f","m","m","m","m","m","f","f")
df=data.frame(spn=x, sex=y)

似乎:

   spn sex
1   01   f
2   01   f
3   01   f
4   22   m
5   22   m
6   03   m
7   03   m
8   03   m
9   35   f
10  35   f

我想做的是对df $ spn进行排序,让它只出现一次.适当的df $性别,如:

   spn sex
1  01   f
2  03   m
3  22   m
4  35   f

我怎么能这样做？非常感谢!

Answer 1

df <- df[order(df$spn), ]
> df[!duplicated(df), ]
  spn sex
1  01   f
6  03   m
4  22   m
9  35   f

Answer 2

df2 = df[!duplicated(df), ] # Remove duplicated rows.
df3 = df2[order(df2$spn), ] # Sort by the spn column.

df3
#  spn sex
#1  01   f
#6  03   m
#4  22   m
#9  35   f