Message-ID: <1505745153.1681.25.camel@pp.inet.fi>
Date: 2017-09-18T14:32:33Z
From: K. Elo
Subject: help matching rows of a data frame
In-Reply-To: <9153c6$7v8l5n@ironport10.mayo.edu>
Hi!
2017-09-18 07:13 -0500, Therneau, Terry M., Ph.D. wrote:
> This question likely has a 1 line answer, I'm just not seeing
> it.??(2, 3, or 10 lines is?
> fine too.)
>
> For a vector I can do group??<- match(x, unqiue(x)) to get a vector
> that labels each?
> element of x.
Actually, you get a vector of indices matching 'unique(x)', not a
labelled vector.
> x<-c("A","B","C","A","C","D")
> group<-match(x, unique(x))
> group
[1] 1 2 3 1 3 4
> What is an equivalent if x is a data frame?
So you will generate an index where duplicated rows have the row index
of the first occurrence, right? This could work:
>?x<-data.frame("X0"=c("A","B","C","C","D","A"), "X1"=c(1,2,1,1,3,1))
> group<-rownames(x)
>?for (i in 1:(nrow(x)-1)) {?
? ? ?for (j in (i+1):nrow(x)) {?
? ? ? ? if (sum(as.numeric(x[i,]==x[j,]))==ncol(x)) {?
? ? ? ? ? ?group[j]<-group[i] }
? ? ?}
? ?}
> ?group
[1] "1" "2" "3" "3" "5" "1"
HTH,
Kimmo