如何根据r中的两个不同列删除重复的行？

Question

I want to delete all the duplicated rows from my data.frame only if their values on another column is different.

Let's say I have a data.frame like this :

Column1 Column2 Column3
A       -       10
A       -       13
A       -       15
B       -       18
B       -       18
B       -       23

The result should be :

Column1 Column2 Column3
A       -       10
B       -       18
B       -       18

Answer 1

df1[ave(df1$Column3, df1$Column1, FUN = function(x) x == x[1]) == 1,]
#  Column1 Column2 Column3
#1       A       -      10
#3       B       -      18
#4       B       -      18