CODEWITHSUNDEEP
raggregate
Nip
Nip

Reputation: 369

How to aggregate some columns while keeping other columns in R?

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?

Upvotes: 18

Views: 35595

Answers (3)

MichaelChirico
MichaelChirico

Reputation: 34763

Even better, data.table:

library(data.table)
# convert your object to a data.table (by reference) to unlock data.table syntax
setDT(DF)
DF[  , .(sum_no = sum(no), unq_age = unique(age)), by = id]

Upvotes: 7

Didzis Elferts
Didzis Elferts

Reputation: 98599

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

Upvotes: 25

Maxim.K
Maxim.K

Reputation: 4180

Alternatively, you could use ddply from plyr package: 

require(plyr)
ddply(df,.(id,age),summarise,no = sum(no))

In this particular example the results are identical. However, this is not always the case, the difference between the both functions is outlined here. Both functions have their uses and are worth exploring, which is why I felt this alternative should be mentioned.

Upvotes: 4

Related Questions