conditionally assign first nth element in vector as H and rests as L

Question

I have a vector of randomly sampled numbers. For example,

vec1 <- sample(1:574)

I would like to assign first 25 percent value in this sample

Answer 1

caretpackage includes createDataPartition function, that will do the job:

library("caret")

SAMPLE_SIZE <- 0.25
SIZE_VECT <- 574

# Set seed for reproducibility
set.seed(pi)

vec1 <- sample(1:SIZE_VECT)

in_sample <- createDataPartition(y = vec1, p = SAMPLE_SIZE, list = FALSE)
H <- vec1[in_sample]
L <- vec1[-in_sample]
# Actual sample size
100 * length(H) / (length(L) + length(H))
#  [1] 25.08711