CODEWITHSUNDEEP
rdataframerank
smz
smz

Reputation: 273

How to rank rows by two columns at once in R?

Here is the code to rank based on column v2:

x <- data.frame(v1 = c(2,1,1,2), v2 = c(1,1,3,2))
x$rank1 <- rank(x$v2, ties.method='first')

But I really want to rank based on both v2 and/then v1 since there are ties in v2. How can I do that without using RPostgreSQL?

Upvotes: 8

Views: 10397

Answers (4)

Ferroao
Ferroao

Reputation: 3066

Try this:

x <- data.frame(v1 = c(2,1,1,2), v2 = c(1,1,3,2))

# The order function returns the index (address) of the desired order 
# of the examined object rows
orderlist<- order(x$v2, x$v1)

# So to get the position of each row in the index, you can do a grep

x$rank<-sapply(1:nrow(x), function(x) grep(paste0("^",x,"$"), orderlist ) )
x

# For a little bit more general case
# With one tie

x <- data.frame(v1 = c(2,1,1,2,2), v2 = c(1,1,3,2,2))

x$rankv2<-rank(x$v2)
x$rankv1<-rank(x$v1)

orderlist<- order(x$rankv2, x$rankv1)  
orderlist

#This rank would not be appropriate
x$rank<-sapply(1:nrow(x), function(x) grep(paste0("^",x,"$"), orderlist ) )

#there are ties
grep(T,duplicated(x$rankv2,x$rankv1) )

# Example for only one tie

makeTieRank<-mean(x[which(x[,"rankv2"] %in% x[grep(T,duplicated(x$rankv2,x$rankv1) ),][,c("rankv2")] &
        x[,"rankv1"] %in% x[grep(T,duplicated(x$rankv2,x$rankv1) ),][,c("rankv1")]),]$rank)

x[which(x[,"rankv2"] %in% x[grep(T,duplicated(x$rankv2,x$rankv1) ),][,c("rankv2")] &
          x[,"rankv1"] %in% x[grep(T,duplicated(x$rankv2,x$rankv1) ),][,c("rankv1")]),]$rank<-makeTieRank
x

Upvotes: 0

user
user

Reputation: 25838

Here we create a sequence of numbers and then reorder it as if it was created near the ordered data:

x$rank <- seq.int(nrow(x))[match(rownames(x),rownames(x[order(x$v2,x$v1),]))]

Or:

x$rank <- (1:nrow(x))[order(order(x$v2,x$v1))]

Or even:

x$rank <- rank(order(order(x$v2,x$v1)))

Upvotes: 0

mmuurr
mmuurr

Reputation: 1580

order works, but for manipulating data frames, also check out the plyr and dplyr packages.

> arranged_x <- arrange(x, v2, v1)

Upvotes: 3

Matthew Plourde
Matthew Plourde

Reputation: 44634

How about:

within(x, rank2 <- rank(order(v2, v1), ties.method='first'))

#   v1 v2 rank1 rank2
# 1  2  1     1     2
# 2  1  1     2     1
# 3  1  3     4     4
# 4  2  2     3     3

Upvotes: 3

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