Sort data frame column by factor

Question

Supose I have a data frame with 3 columns (name, y, sex) where name is character, y is a numeric value and <

Answer 1

Here is a summary of all methods mentioned in other answers/comments (to serve future searchers). I've added a data.table way of sorting.

# Base R
do.call(rbind, by(score, score$sex, function(x) x[order(x$y),]))
with(score, score[order(sex, y, x),])
score[order(score$sex,score$x),]

# Using plyr
arrange(score, sex,y)
ddply(score, c('sex', 'y'))

# Using `data.table`
library("data.table")
score_dt <- setDT(score)

# setting a key works sorts the data.table
setkey(score_dt,sex,x)
print(score_dt)

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