Add Specify How Random Array Sample Is as a Ruby TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1396 TILs and counting..._
+_1397 TILs and counting..._
 
 ---
 
@@ -1187,6 +1187,7 @@ _1396 TILs and counting..._
 - [Single And Double Quoted String Notation](ruby/single-and-double-quoted-string-notation.md)
 - [Skip Specific CVEs When Auditing Your Bundle](ruby/skip-specific-cves-when-auditing-your-bundle.md)
 - [Specify Dependencies For A Rake Task](ruby/specify-dependencies-for-a-rake-task.md)
+- [Specify How Random Array#sample Is](ruby/specify-how-random-array-sample-is.md)
 - [Split A Float Into Its Integer And Decimal](ruby/split-a-float-into-its-integer-and-decimal.md)
 - [Squeeze Out The Extra Space](ruby/squeeze-out-the-extra-space.md)
 - [String Interpolation With Instance Variables](ruby/string-interpolation-with-instance-variables.md)

ruby/specify-how-random-array-sample-is.md

@@ -0,0 +1,46 @@
+# Specify How Random Array#sample Is
+
+A typical use of the
+[`sample`](https://ruby-doc.org/core-2.4.0/Array.html#method-i-sample) method
+on [`Array`](https://ruby-doc.org/core-2.4.0/Array.html) will look something
+like this:
+
+```ruby
+> chars = [('a'..'z'), ('A'..'Z'), ('0'..'9')].map(&:to_a).flatten
+
+> chars.sample(6)
+=> ["o", "Z", "X", "i", "8", "Y"]
+```
+
+By default, this is using `Random` (a pseudo-random number generator) to
+produce a _random_ sampling of elements from your array.
+
+The longer form of this looks like:
+
+```ruby
+> chars.sample(6, random: Random)
+=> ["F", "c", "g", "I", "w", "E"]
+```
+
+Or to get reproducible results, you can specify the `Random` seed:
+
+```ruby
+> chars.sample(6, random: Random.new(123))
+=> ["T", "c", "D", "K", "P", "s"]
+```
+
+If instead you want a cryptographically random sampling of elements from your
+array, you can specify a different random number generator. Such as
+[`SecureRandom`](https://ruby-doc.org/stdlib-2.5.1/libdoc/securerandom/rdoc/SecureRandom.html).
+
+```ruby
+> require 'securerandom'
+=> true
+
+> chars.sample(6, random: SecureRandom)
+=> ["3", "C", "o", "i", "K", "4"]
+```
+
+The
+[`Array#shuffle`](https://ruby-doc.org/core-2.4.0/Array.html#method-i-shuffle)
+method is another example of a method that can take a `random` option.