How to aggregate some columns while keeping other columns in R?
aggregate, r
Solution
Assuming that your data frame is named `df`.
aggregate(no~id+age, df, sum)
# id age no
# 1 1 23 9
# 2 3 23 7
# 3 2 25 5
Problem
I have a data frame like this: ``` id no age 1 1 7 23 2 1 2 23 3 2 1 25 4 2 4 25 5 3 6 23 6 3 1 23 ``` and I hope to aggregate the date frame by `id` to a form like this: (just sum the `no` if they share the same `id`, but keep `age` there) ``` id no age 1 1 9 23 2 2 5 25 3 3 7 23 ``` How to achieve this using R?