CODEWITHSUNDEEP
rstatisticss-plus
Ryan Guest
Ryan Guest

Reputation: 6470

In R, what is a good way to aggregate String data

In R (or S-PLUS), what is a good way to aggregate String data in a data frame?

Consider the following:

myList <- as.data.frame(c("Bob", "Mary", "Bob", "Bob", "Joe"))

I would like the output to be:

 [Bob,  3
  Mary, 1
  Joe,  1]

Currently, the only way I know how to do this is with the summary function.

> summary(as.data.frame(myList))

 Bob :3                                
 Joe :1                                
 Mary:1

This feels like a hack. Can anyone suggest a better way?

Upvotes: 1

Views: 1165

Answers (5)

Chriss Paul
Chriss Paul

Reputation: 1101

Using data.table 

myList <- data.frame(v1=c("Bob", "Mary", "Bob", "Bob", "Joe"))
library(data.table)
     v1 N
1:  Bob 3
2: Mary 1
3:  Joe 1

Upvotes: 1

OmG
OmG

Reputation: 18838

Using sqldf library:

require(sqldf)

myList<- data.frame(v=c("Bob", "Mary", "Bob", "Bob", "Joe"))
sqldf("SELECT v,count(1) FROM myList GROUP BY v")

Upvotes: 0

Jouni K. Sepp&#228;nen
Jouni K. Sepp&#228;nen

Reputation: 44128

Do you mean like this?

myList <- c("Bob", "Mary", "Bob", "Bob", "Joe")
r <- rle(sort(myList))
result <- as.data.frame(cbind(r$values, r$lengths))
names(result) <- c("Name", "Occurrences")
result
  Name Occurrences
1  Bob           3
2  Joe           1
3 Mary           1

Upvotes: 1

andrewj
andrewj

Reputation: 3035

This is a combination of the above answers (as suggested by Thierry)

data.frame(table(myList[,1]))

which gives you

  Var1 Freq
1  Bob    3
2  Joe    1
3 Mary    1

Upvotes: 2

bubaker
bubaker

Reputation: 2289

Using table, no need to sort:

ctable <- table(myList);
counts <- data.frame(Name = names(ctable),Count = as.vector(ctable));

Upvotes: 2

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