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ruby-on-railsrubystatisticsprobability

Best algorithm for x% chance of happening?

I need to make an event occur on a configurable x% of pageviews across all pageviews.

I want to make sure I'm thinking of the probability correctly here.

The following code runs every single pageview.

if I want event to occur 99% of the time

do_thing if SecureRandom.random_number(1..100) <= 99

if I want event to occur 10% of the time

do_thing if SecureRandom.random_number(1..100) <= 10

I know there are subtle nuance "gotchas" in probability and I wanted to make sure this is the best approach.

Solution

  • Your solution is ok in terms of probability calculations. But I would use the ruby method Kernel#rand instead to save some space:

    rand * 100 <= 99 or rand(1..100) <= 99