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Wraps its argument in an array unless it is already an array (or array-like).
Specifically:
-
If the argument is
nil
an empty list is returned. -
Otherwise, if the argument responds to
to_ary
it is invoked, and its result returned. -
Otherwise, returns an array with the argument as its single element.
::wrap # => [] ::wrap([1, 2, 3]) # => [1, 2, 3] ::wrap # => [0]
This method is similar in purpose to Kernel#Array
, but there
are some differences:
-
If the argument responds to
to_ary
the method is invoked.Kernel#Array
moves on to try to_a
if the returned value is
nil
, but Array.wrap
returns such a
nil
right away.
-
If the returned value from
to_ary
is neithernil
nor anArray
object,Kernel#Array
raises an exception, while Array.wrap
does not, it just
returns the value.
-
It does not call
to_a
on the argument, though special-casesnil
to return an empty array.
The last point is particularly worth comparing for some enumerables:
Array(:foo => :bar) # => [[:foo, :bar]] Array.wrap(:foo => :bar) # => [{:foo => :bar}] Array("foo\nbar") # => ["foo\n", "bar"], in Ruby 1.8 Array.wrap("foo\nbar") # => ["foo\nbar"]
There's also a related idiom that uses the splat operator:
[*object]
which returns [nil]
for nil
, and calls to
Array(object)
otherwise.
Thus, in this case the behavior is different for nil
, and the
differences with Kernel#Array
explained above apply to the
rest of +object+s.
Extracts options from a set of arguments. Removes and returns the last element in the array if it's a hash, otherwise returns a blank hash.
def options(*args) args.extract_options! end options(1, 2) # => {} options(1, 2, :a => :b) # => {:a=>:b}
Equal to self[4]
.
Equal to self[41]
. Also known as accessing “the reddit”.
Equal to self[3]
.
Returns the tail of the array from position
.
%w( a b c d ).from(0) # => %w( a b c d ) %w( a b c d ).from(2) # => %w( c d ) %w( a b c d ).from(10) # => %w() %w().from(0) # => %w()
Splits or iterates over the array in number
of groups, padding
any remaining slots with fill_with
unless it is
false
.
%w(1 2 3 4 5 6 7 8 9 10).in_groups(3) {|group| p group} ["1", "2", "3", "4"] ["5", "6", "7", nil] ["8", "9", "10", nil] %w(1 2 3 4 5 6 7).in_groups(3, ' ') {|group| p group} ["1", "2", "3"] ["4", "5", " "] ["6", "7", " "] %w(1 2 3 4 5 6 7).in_groups(3, false) {|group| p group} ["1", "2", "3"] ["4", "5"] ["6", "7"]
# File activesupport/lib/active_support/core_ext/array/grouping.rb, line 56 def in_groups(number, fill_with = nil) # size / number gives minor group size; # size % number gives how many objects need extra accommodation; # each group hold either division or division + 1 items. division = size / number modulo = size % number # create a new array avoiding dup groups = [] start = 0 number.times do |index| length = division + (modulo > 0 && modulo > index ? 1 : 0) padding = fill_with != false && modulo > 0 && length == division ? 1 : 0 groups << slice(start, length).concat([fill_with] * padding) start += length end if block_given? groups.each { |g| yield(g) } else groups end end
Splits or iterates over the array in groups of size number
,
padding any remaining slots with fill_with
unless it is
false
.
%w(1 2 3 4 5 6 7).in_groups_of(3) {|group| p group} ["1", "2", "3"] ["4", "5", "6"] ["7", nil, nil] %w(1 2 3).in_groups_of(2, ' ') {|group| p group} ["1", "2"] ["3", " "] %w(1 2 3).in_groups_of(2, false) {|group| p group} ["1", "2"] ["3"]
# File activesupport/lib/active_support/core_ext/array/grouping.rb, line 19 def in_groups_of(number, fill_with = nil) if fill_with == false collection = self else # size % number gives how many extra we have; # subtracting from number gives how many to add; # modulo number ensures we don't add group of just fill. padding = (number - size % number) % number collection = dup.concat([fill_with] * padding) end if block_given? collection.each_slice(number) { |slice| yield(slice) } else groups = [] collection.each_slice(number) { |group| groups << group } groups end end
Backport of #sample based on
Marc-Andre Lafortune's github.com/marcandre/backports/
Returns a random element or n
random elements from the array.
If the array is empty and n
is nil, returns nil
.
If n
is passed and its value is less than 0, it raises an
ArgumentError
exception. If the value of n
is
equal or greater than 0 it returns []
.
[1,2,3,4,5,6].sample # => 4 [1,2,3,4,5,6].sample(3) # => [2, 4, 5] [1,2,3,4,5,6].sample(-3) # => ArgumentError: negative array size [].sample # => nil [].sample(3) # => []
# File activesupport/lib/active_support/core_ext/array/random_access.rb, line 13 def sample(n=nil) return self[Kernel.rand(size)] if n.nil? n = n.to_int rescue Exception => e raise TypeError, "Coercion error: #{n.inspect}.to_int => Integer failed:\n(#{e.message})" else raise TypeError, "Coercion error: obj.to_int did NOT return an Integer (was #{n.class})" unless n.kind_of? Integer raise ArgumentError, "negative array size" if n < 0 n = size if n > size result = Array.new(self) n.times do |i| r = i + Kernel.rand(size - i) result[i], result[r] = result[r], result[i] end result[n..size] = [] result end
Equal to self[1]
.
Divides the array into one or more subarrays based on a delimiting
value
or the result of an optional block.
[1, 2, 3, 4, 5].split(3) # => [[1, 2], [4, 5]] (1..10).to_a.split { |i| i % 3 == 0 } # => [[1, 2], [4, 5], [7, 8], [10]]
# File activesupport/lib/active_support/core_ext/array/grouping.rb, line 87 def split(value = nil) using_block = block_given? inject([[]]) do |results, element| if (using_block && yield(element)) || (value == element) results << [] else results.last << element end results end end
Equal to self[2]
.
Returns the beginning of the array up to position
.
%w( a b c d ).to(0) # => %w( a ) %w( a b c d ).to(2) # => %w( a b c ) %w( a b c d ).to(10) # => %w( a b c d ) %w().to(0) # => %w()
Converts a collection of elements into a formatted string by calling
to_s
on all elements and joining them:
Blog.all.to_formatted_s # => "First PostSecond PostThird Post"
Adding in the :db
argument as the format yields a comma
separated id list:
Blog.all.to_formatted_s(:db) # => "1,2,3"
Calls to_param
on all its elements and joins the result with
slashes. This is used by url_for
in Action Pack.
Converts an array into a string suitable for use as a URL query string,
using the given key
as the param name.
['Rails', 'coding'].to_query('hobbies') # => "hobbies%5B%5D=Rails&hobbies%5B%5D=coding"
Converts the array to a comma-separated sentence where the last element is joined by the connector word. Options:
-
:words_connector
- The sign or word used to join the elements in arrays with two or more elements (default: “, ”) -
:two_words_connector
- The sign or word used to join the elements in arrays with two elements (default: “ and ”) -
:last_word_connector
- The sign or word used to join the last element in arrays with three or more elements (default: “, and ”)
# File activesupport/lib/active_support/core_ext/array/conversions.rb, line 11 def to_sentence(options = {}) if defined?(I18n) default_words_connector = I18n.translate(:'support.array.words_connector', :locale => options[:locale]) default_two_words_connector = I18n.translate(:'support.array.two_words_connector', :locale => options[:locale]) default_last_word_connector = I18n.translate(:'support.array.last_word_connector', :locale => options[:locale]) else default_words_connector = ", " default_two_words_connector = " and " default_last_word_connector = ", and " end options.assert_valid_keys(:words_connector, :two_words_connector, :last_word_connector, :locale) options.reverse_merge! :words_connector => default_words_connector, :two_words_connector => default_two_words_connector, :last_word_connector => default_last_word_connector case length when 0 "" when 1 self[0].to_s.dup when 2 "#{self[0]}#{options[:two_words_connector]}#{self[1]}" else "#{self[0...-1].join(options[:words_connector])}#{options[:last_word_connector]}#{self[-1]}" end end
Returns a string that represents the array in XML by invoking
to_xml
on each element. Active Record collections delegate
their representation in XML to this method.
All elements are expected to respond to to_xml
, if any of them
does not then an exception is raised.
The root node reflects the class name of the first element in plural if all elements belong to the same type and that's not Hash:
customer.projects.to_xml <?xml version="1.0" encoding="UTF-8"?> <projects type="array"> <project> <amount type="decimal">20000.0</amount> <customer-id type="integer">1567</customer-id> <deal-date type="date">2008-04-09</deal-date> ... </project> <project> <amount type="decimal">57230.0</amount> <customer-id type="integer">1567</customer-id> <deal-date type="date">2008-04-15</deal-date> ... </project> </projects>
Otherwise the root element is “records”:
[{:foo => 1, :bar => 2}, {:baz => 3}].to_xml <xml version="1.0" encoding="UTF-8"?> <records type="array"> <record> <bar type="integer">2</bar> <foo type="integer">1</foo> </record> <record> <baz type="integer">3</baz> </record> </records>
If the collection is empty the root element is “nil-classes” by default:
[].to_xml <?xml version="1.0" encoding="UTF-8"?> <nil-classes type="array"/>
To ensure a meaningful root element use the :root
option:
customer_with_no_projects.projects.to_xml(:root => "projects") <xml version="1.0" encoding="UTF-8"?> <projects type="array"/>
By default name of the node for the children of root is
root.singularize
. You can change it with the
:children
option.
The options
hash is passed downwards:
Message.all.to_xml(:skip_types => true) <xml version="1.0" encoding="UTF-8"?> <messages> <message> <created-at>2008-03-07T09:58:18+01:00</created-at> <id>1</d> <name>1</name> <updated-at>2008-03-07T09:58:18+01:00</pdated-at> <user-id>1</user-id> </essage> </messages>
# File activesupport/lib/active_support/core_ext/array/conversions.rb, line 136 def to_xml(options = {}) require 'active_support/builder' unless defined?(Builder) options = options.dup options[:indent] ||= 2 options[:builder] ||= Builder::XmlMarkup.new(:indent => options[:indent]) options[:root] ||= if first.class.to_s != "Hash" && all? { |e| e.is_a?(first.class) } underscored = ActiveSupport::Inflector.underscore(first.class.name) ActiveSupport::Inflector.pluralize(underscored).tr('/', '_') else "objects" end builder = options[:builder] builder.instruct! unless options.delete(:skip_instruct) root = ActiveSupport::XmlMini.rename_key(options[:root].to_s, options) children = options.delete(:children) || root.singularize attributes = options[:skip_types] ? {} : {:type => "array"} return builder.tag!(root, attributes) if empty? builder.__send__(:method_missing, root, attributes) do each { |value| ActiveSupport::XmlMini.to_tag(children, value, options) } yield builder if block_given? end end
Returns an unique array based on the criteria given as a Proc
.
[1, 2, 3, 4].uniq_by { |i| i.odd? } # => [1, 2]