CODEWITHSUNDEEP
r
Kenji
Kenji

Reputation: 581

R, aggregate( ) using table( ) as a function

I have dataset that looks like this but much larger:

data <- data.frame(cbind(c(1,1,1,1,1,1,2,2,2),
                         c(1,1,1,2,2,2,1,1,1),
                         c(1,2,2,2,3,3,1,2,1)))
data$X3<-factor(data$X3)
levels(data$X3)<-c("House","Barn","Pigsty")

I want to have a dataset with counts of "House," "Barn," and "Pigsty" by X1 and X2. Imagine that X and Y are coordinates and that I want to count how many of each type of building I have at each coordinate.

I am doing:

agdata <- aggregate(data[,"X3"],by=list(data[,"X1"],data[,"X2"]),FUN=table)

If I ask to print agdata by using head(agdata), it shows me the two coordinates and the three count variables for each level of X3:

  > head(agdata)
     Group.1 Group.2  x.House  x.Barn   x.Pigsty

   1       1       1       1      2        0    
   2       2       1       2      1        0    
   3       1       2       0      1        2

However, if I use View(agdata) I only see three variables Group.1 ,Group2 ,and x.

How can I get aggregate to give me a dataset in the format that I see when I use head(agdata)?

Upvotes: 0

Views: 137

Answers (1)

Manuel Ram&#243;n
Manuel Ram&#243;n

Reputation: 2498

You could get it using dcast from reshape2 package:

library(reshape2)
dcast(data, X1+X2 ~ X3)

Upvotes: 1

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