Performance-Sample.md

Pattern: Missing use of sample

Issue: -

Description

This rule is used to identify usages of shuffle.first, shuffle.last and shuffle[] and change them to use sample instead.

Examples

# bad
[1, 2, 3].shuffle.first
[1, 2, 3].shuffle.first(2)
[1, 2, 3].shuffle.last
[1, 2, 3].shuffle[2]
[1, 2, 3].shuffle[0, 2]    # sample(2) will do the same
[1, 2, 3].shuffle[0..2]    # sample(3) will do the same
[1, 2, 3].shuffle(random: Random.new).first

# good
[1, 2, 3].shuffle
[1, 2, 3].sample
[1, 2, 3].sample(3)
[1, 2, 3].shuffle[1, 3]    # sample(3) might return a longer Array
[1, 2, 3].shuffle[1..3]    # sample(3) might return a longer Array
[1, 2, 3].shuffle[foo, bar]
[1, 2, 3].shuffle(random: Random.new)

Further Reading

• RuboCop - Performance/Sample
• https://github.com/JuanitoFatas/fast-ruby#arrayshufflefirst-vs-arraysample-code