Sampling a random integer sequence

This function provides a very efficient way to pull an integer random sample sequence from an integer interval.

Usage

sample_seq(low, high, length)

Arguments

low: The lower limit of the interval (inclusive).
high: The higher limit of the interval (inclusive).
length: The length of the sample.

Value

An increasing numeric vector containing integers, the sample.

Details

The algorithm runs in O(length) expected time, even if high-low is big. It is much faster (but of course less general) than the builtin sample function of R.

References

Jeffrey Scott Vitter: An Efficient Algorithm for Sequential Random Sampling, ACM Transactions on Mathematical Software, 13/1, 58–67.

Author

Gabor Csardi csardi.gabor@gmail.com

Examples


rs <- sample_seq(1, 100000000, 10)
rs
#>  [1]  4593302  6258982 21609001 24855955 39332722 42992613 57436748 75224546
#>  [9] 81610907 84302008