Bogs - 6 months ago 15

R Question

I have the following data (this is a mock version) and I am using R.

`ID m`

1 m1

1 m2

1 m3

2 m1

2 m2

3 m1

3 m2

3 m3

3 m4

4 m1

Each ID has an m1 row and the rest of the m's are of variable length amongst the ID's. I would like to keep the m1 value and the last value corresponding to each ID. The ideal output would look like this:

`ID m`

1 m1

1 m3

2 m1

2 m2

3 m1

3 m4

4 m1

Thank you very much in advance.

Answer

The same result with `dplyr`

:

```
df %>%
group_by(ID) %>%
filter(row_number()==n()|m=='m1')
Source: local data frame [7 x 2]
Groups: ID
ID m
1 1 m1
2 1 m3
3 2 m1
4 2 m2
5 3 m1
6 3 m4
7 4 m1
```