How to assign the rank to the arranged dataframe (based on group)

tidyverse
,
1

How can we add the rank for each arranged dataframe ?

How can we add another column called rank which
describes the rank for that group.

e.g.
Species class value rank

1 setosa Petal.Width 0.1 1
2 setosa Petal.Width 0.1 2
3 setosa Petal.Width 0.1 3

Similarly however, this rank does not rank all 600 rows instead.
It should start and end within the group.

library(tidyr)
my_df =iris %>% pivot_longer(names_to = "class", cols = c(1:4))

op = my_df %>% group_by(Species, class) %>%
  arrange(value)

 my_df %>% group_by(Species, class) %>%
+   arrange(value)
# A tibble: 600 x 3
# Groups:   Species, class [12]
   Species class       value
   <fct>   <chr>       <dbl>
 1 setosa  Petal.Width   0.1
 2 setosa  Petal.Width   0.1
 3 setosa  Petal.Width   0.1
 4 setosa  Petal.Width   0.1
 5 setosa  Petal.Width   0.1
 6 setosa  Petal.Width   0.2
 7 setosa  Petal.Width   0.2
 8 setosa  Petal.Width   0.2
 9 setosa  Petal.Width   0.2
10 setosa  Petal.Width   0.2
# … with 590 more rows
2

Have you tried

op <-  my_df %>% group_by(Species, class) %>%
	mutate(rank = rank(value)) %>% 
	arrange(value)

... there are quite a few options in rank how to deal with ties.

2 Likes
3

Thanks for quick help.

tried your approach but rank is integer which is undesired

> op$rank %>% unique()
 [1]  3.0 20.0 38.0 45.0 49.0 50.0  1.0  4.0  2.0  9.0  3.5 13.0  8.0 22.0 18.0 32.0 31.0 40.5  2.5 41.0 47.0 46.5  5.0 11.0 49.5 19.0 24.5 30.5 35.0 46.0 11.5 15.0  6.5  9.5 15.5
[36] 20.5  5.5 38.5 27.5 10.5 44.0 35.5 40.0 18.5 24.0 31.5  4.5 36.0  6.0 48.0 39.0  7.0 42.5 45.5 10.0 14.0 21.5 33.0  7.5 42.0 47.5 32.5 17.5 19.5 43.0 28.5 48.5 23.0 25.5  8.5
[71] 12.5 16.5 26.5 43.5 34.5 37.0
4

What would you like it to be? :slight_smile:

5

basically, rank meaning... row number

6

So, you mean like this?

op <-  my_df %>% group_by(Species, class) %>%
	mutate(rank = rank(value, ties.method = "first")) %>% 
	arrange(value)
2 Likes
7

Can we retain this format but excluding integer values ?

Meaning, repetition is ok but not integer in the rank column

8

Hi @AbhishekHP,

again, I am not quite sure what you mean ... by default rank uses ties.method = 'average' which results in ranks like you see in my first response (which are not integers by the way). With ties.method = 'first' you get the rank in fact as integers from 1 to as many values there are in each group. So ... not sure which one you prefer - you can also check the documentation for rank for other methods.

9

Thanks for response.
Was wondering if we can somehow get rid of averaging only if they appear to be integer.
However, let me proceed with ties.method = "first"

10

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