[R] Remove duplicate rows based on condition

arun smartpink111 at yahoo.com
Fri Feb 7 17:58:11 CET 2014

If I understand it correctly, you could use ?unique() or ?duplicated()




Hello everyone. I am very new to R and very bad in programming. 
I need to remove some rows based on multiple conditions. 
For example, I have this table: 

Id = c(1,1,2,2,3,3) 
url = c("a", "b", "a", "a", "b","b") 
mydf = data.frame(Id,url) 

I want to remove the second row of url of the same Id, but keep both rows of 
url if they are different. 

Thank you very much.

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