CODEWITHSUNDEEP
rsortingdataframeplyr
tomathon
tomathon

Reputation: 854

Ordering data frame in R

I have the following data frame structure:

    Animal          Food
1    cat      fish, milk, shrimp
2    dog      steak, poo
3    fish     seaweed, shrimp, krill, insects

I would like to reorganize it so that the rows are in descending order of number of factors in the "Food" column:

    Animal          Food
1    fish     seaweed, shrimp, krill, insects
2    cat      fish, milk, shrimp
3    dog      steak, poo

Is there an R function that can help me with that? Thanks

Upvotes: 0

Views: 266

Answers (3)

crogg01
crogg01

Reputation: 2526

You can order the frame according to the results of your counting function:

animals = data.frame( rbind(c("cat","fish, milk, shrimp"),
                  c("dog","steak, poo"),
                  c("fish","seaweed, shrimp, krill, insects")))
colnames(animals) = c("Animal","Food")
animals[order(sapply(animals$Food, function(x) { length(strsplit(as.character(x),split=",")[[1]]) })), ]

I put in the as.character because it defaults to a factor, you probably don't need it (quicker) alternatively you can use stringsAsFactors=FALSE when creating the data frame.

Upvotes: 1

Ananta
Ananta

Reputation: 3711

make a new variable and sort by that, edit: thanks to Ananda and alexis

df$nFood<-length(unlist(strsplit(df$Food, ",", fixed=T)))

df$nFood<-sapply(strsplit(df$Food, ","), length)

Upvotes: 1

A5C1D2H2I1M1N2O1R2T1
A5C1D2H2I1M1N2O1R2T1

Reputation: 193517

You can use count.fields to figure out how many items there are in each "food" row and order by that. 

count.fields(textConnection(mydf$Food), ",")
# [1] 3 2 4

Assuming your data.frame is called "mydf":

mydf[order(count.fields(textConnection(mydf$Food), ","), decreasing=TRUE),]
#   Animal                            Food
# 3   fish seaweed, shrimp, krill, insects
# 1    cat              fish, milk, shrimp
# 2    dog                      steak, poo

Upvotes: 4

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