如何从R数据框中的索引列获取唯一行

Question

Here is a reproducible dataset https://drive.google.com/file/d/0B3cafW7J7xSfNmhJQzh3SF9VYms/edit?usp=sharing

I want to delete all the rows which have a same value as the first column of accident index. means that here in data frame if there are 2-3 rows with the first column value same then only 1st row should be kept and others deleted.

I tried the following but it didn't work.

v2<-v1[which(v1$i..Accident_Index==unique(v1$i..Accident_Index))]

Please help..thanks

Answer 1

You can try:

v2 <- v1[!duplicated(v1$i..Accident_Index), ]

To demonstrate this does answer the question:

v1 <- data.frame(i..Accident_Index=rep(1:3, each=2), b=letters[1:6])
v1[!duplicated(v1$i..Accident_Index), ]

Produces:

  i..Accident_Index b
1                 1 a
3                 2 c
5                 3 e