CODEWITHSUNDEEP
rdplyr
Patrick Balada
Patrick Balada

Reputation: 1450

How to rank values in a data frame rowwise using dplyr?

The question is straightforward. I started using dplyr but cannot come up with a solution of how to rank the values in each row. The ultimate goal would be to assign a rank to each value and for each row. I tried the following that didn't work:

mat_agg %>% rowwise() %>% mutate_each(funs(rank))

An example is:

matrix(c(1,0,0.5,0.5, 0, 1),nrow=2)

The desired outcome would be:

matrix(c(1,3,2,2, 3, 1),nrow=2)

I very much appreciate any help. Thank you!

Upvotes: 2

Views: 1875

Answers (2)

akrun
akrun

Reputation: 886938

If we are using dplyr, convert the matrix to data.frame, and use do with rowwise

library(dplyr)
data.frame(m1) %>%
         rowwise() %>% 
         do(data.frame(t(rank(-unlist(.)))))
#      X1    X2    X3
#  (dbl) (dbl) (dbl)
#1     1     2     3
#2     3     2     1

Upvotes: 3

mtoto
mtoto

Reputation: 24178

We can use apply() in combination with rank(). We negate m to get descending order, and transpose the output to get desired structure.

t(apply(-m,1,rank))
#     [,1] [,2] [,3]
#[1,]    1    2    3
#[2,]    3    2    1

Upvotes: 6

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