通过删除因子的每个级别的重复项来子集数据帧

Question

I have a data frame:

df<- data.frame(region= c("1", "1", "1","1","1","1","1","1","2","2"),
            plot=c("1", "1", "1","2","2","2", "3","3","3","3"),
            interact=c("A_B", "C_D","C_D", "E_F","C_D","C_D", "D_E", 
            "D_E","C_B","A_B"))

And I would like to get count of all unique levels of interact for each plot subset. The final data frame would look like:

 result<- 
     Plot    freq
      1      2
      2      2
      3      3

I would like to use dplyr and have gotten this far:

 df2 <-df %>% group_by(plot) %>%mutate(freq=length(unique((interact))))

But with the code above I have yet to figure out a way where only one value per plot is represented (ie. duplicate values in freq for each unique plot are removed).

Answer 1

Try this .

df%>%group_by(plot)%>%summarise(n=length(unique(interact)))

    plot     n
1      1     2
2      2     2
3      3     3

or base on your own way.

df2 <-df %>% group_by(plot) %>%mutate(freq=length(unique((interact))))
df2=df2[!duplicated(df2$plot),]

  region   plot interact  freq
  <fctr> <fctr>   <fctr> <int>
1      1      1      A_B     2
2      1      2      E_F     2
3      1      3      D_E     3