Filtering an array in Ruby by character properties

ruby_array_filter.rb

# A simple implementation of character-based filtering in Ruby, covering different edge cases and use scenarios.
def filter_array(input)
  # Filter array for numbers
  num_array = input.select { |item| item =~ /\d/ }

  # Filter array for capitals
  capital_array = input.select do |item|
    item =~ /^[A-Z]+$/ ? true : false
  end.compact

  # Filter array for lower case letters only
  lower_case_array = input.select { |item| item =~ /^[a-z]+$/ }

  # Filter array for only a-z no numbers
  alpha_no_num_array = input.select do |item|
    item =~ /^[a-zA-Z]+$/ ? true : false
  end.compact

  # Filter array for arrays with at least one capital letter
  mixed_case_array = input.select do |item|
    item =~ /[A-Z]/ ? true : false
  end.compact

  [num_array, capital_array, lower_case_array, alpha_no_num_array, mixed_case_array]
end

input = [
  # all numbers
  "12345", "67890", "1234567890",
  # all capitals
  "ABCDEFGHIJKLMNOPQRSTUVWXYZ", "abcdefghij", "KOKKOK",
  # lower case only
  "abcdefghijklmnopqrstuvwxyz", "hello world",
  # mix of upper and lower case letters
  "AbCdefGhIjKlMnOpQrStUvWxYz", "aBcDeFgHiJkLmNoPqRsTuVwXyZ",
  # strings with numbers
  "Hello World! 12345", "foo bar 67890", "test string 1234567890",
  # strings with special characters
  "!@#$%^&*()", "?_+~`[]{}|;:,.<>?/\\", "@#$%$&*()",
  # all combinations of uppercase and lowercase letters, digits, and special characters
  "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz!", "12345678901234567890!@#$%^&*()",
  # empty strings
  "", "   ",
  # long strings
  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()" * 100,
  "Hello World! 12345 67890 1234567890!" * 100
]
results = filter_array(input)

puts "Numbers: #{results[0]}"
puts "Capitals: #{results[1]}"
puts "Lower case only: #{results[2]}"
puts "Only a-z no numbers: #{results[3]}"
puts "Arrays with at least one capital letter: #{results[4]}"