Sample k rows from data frame and create identifier for which rows are selected in R

Asked Dec 08 '15 at 15:15

Active Dec 08 '15 at 16:22

Viewed 45 times

My question relates to this famous question. I want to select rows from a data frame

k=3
df = data.frame(matrix(rnorm(20), nrow=10))
selected.rows = df[sample(nrow(df), k), ]

But instead of a new data.frame with k rows, I want a column vector in df indicating which rows are selected. I obviously cannot use

sample(c(0,1),nrow(df),TRUE)

Because then k cannot be specified. But something along these lines should give a solution.

edited May 23 '17 at 11:52

Community

asked Dec 08 '15 at 15:15

tomka

2

what about `sample(c(rep(1, k), rep(0, nrow(df)-k)), FALSE)` ? – Cath Dec 08 '15 at 15:19
3

You could try something along the lines of `df$select <- 1:nrow(df) %in% sample(nrow(df), k)` – Heroka Dec 08 '15 at 15:19
Ah perfect solutions both. @Heroka Just had the same thought (but that's easy to say now). – tomka Dec 08 '15 at 15:21

0 Answers0