user1872443 - 5 months ago 41

R Question

In R I have a dataframe with two columns one is a value and the other is the group that each value is assigned to:

`my_group my_value`

A 1.2

B 5.4

C 9.2

A 1.1

B 5.2

C 9.8

A 1.3

B 5.1

C 9.2

A 1.0

B 5.7

C 9.1

I want to create a third column that uses the average of my_value by group to rank the groups and enters that rank in each row:

`my_group my_value my_group_rank`

A 1.2 3

B 5.4 2

C 9.2 1

A 1.1 3

B 5.2 2

C 9.8 1

A 1.3 3

B 5.1 2

C 9.2 1

A 1.0 3

B 5.7 2

C 9.1 1

Answer

The following code will add the group ranks to your data, except that the ranks will be in opposite order, perhaps you can still use it. I use the package `dplyr`

for this. In my example, I assume your data is in a data.frame called `test`

.

```
require(dplyr)
test <- test %>%
group_by(my_group) %>%
mutate(avg = mean(my_value)) %>%
ungroup() %>%
mutate(my_group_rank = dense_rank(avg)) %>%
select(-avg)
# my_group my_value my_group_rank
#1 A 1.2 1
#2 B 5.4 2
#3 C 10.2 3
#4 A 1.1 1
#5 B 5.2 2
#6 C 9.8 3
#7 A 1.3 1
#8 B 5.1 2
#9 C 9.2 3
#10 A 1.0 1
#11 B 5.7 2
#12 C 10.1 3
```