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47 lines
1.3 KiB
Markdown
47 lines
1.3 KiB
Markdown
# Specify How Random Array#sample Is
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A typical use of the
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[`sample`](https://ruby-doc.org/core-2.4.0/Array.html#method-i-sample) method
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on [`Array`](https://ruby-doc.org/core-2.4.0/Array.html) will look something
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like this:
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```ruby
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> chars = [('a'..'z'), ('A'..'Z'), ('0'..'9')].map(&:to_a).flatten
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> chars.sample(6)
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=> ["o", "Z", "X", "i", "8", "Y"]
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```
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By default, this is using `Random` (a pseudo-random number generator) to
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produce a _random_ sampling of elements from your array.
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The longer form of this looks like:
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```ruby
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> chars.sample(6, random: Random)
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=> ["F", "c", "g", "I", "w", "E"]
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```
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Or to get reproducible results, you can specify the `Random` seed:
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```ruby
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> chars.sample(6, random: Random.new(123))
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=> ["T", "c", "D", "K", "P", "s"]
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```
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If instead you want a cryptographically random sampling of elements from your
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array, you can specify a different random number generator. Such as
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[`SecureRandom`](https://ruby-doc.org/stdlib-2.5.1/libdoc/securerandom/rdoc/SecureRandom.html).
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```ruby
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> require 'securerandom'
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=> true
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> chars.sample(6, random: SecureRandom)
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=> ["3", "C", "o", "i", "K", "4"]
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```
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The
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[`Array#shuffle`](https://ruby-doc.org/core-2.4.0/Array.html#method-i-shuffle)
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method is another example of a method that can take a `random` option.
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