An Array is an ordered, integer-indexed collection of objects, called elements. Any object (even another array) may be an array element, and an array can contain objects of different types.
Array indexing starts at 0, as in C or Java.
A positive index is an offset from the first element:
Index 0 indicates the first element.
Index 1 indicates the second element.
…
A negative index is an offset, backwards, from the end of the array:
Index -1 indicates the last element.
Index -2 indicates the next-to-last element.
…
A non-negative index is in range if and only if it is smaller than the size of the array. For a 3-element array:
Indexes 0 through 2 are in range.
Index 3 is out of range.
A negative index is in range if and only if its absolute value is not larger than the size of the array. For a 3-element array:
Indexes -1 through -3 are in range.
Index -4 is out of range.
Although the effective index into an array is always an integer, some methods (both within and outside of class Array) accept one or more non-integer arguments that are integer-convertible objects.
You can create an Array object explicitly with:
An array literal:
[1, 'one', :one, [2, 'two', :two]]
A array literal:
%w[foo bar baz] # => ["foo", "bar", "baz"] %w[1 % *] # => ["1", "%", "*"]
A array literal:
%i[foo bar baz] # => [:foo, :bar, :baz] %i[1 % *] # => [:"1", :%, :*]
Method Kernel#Array
:
Array(["a", "b"]) # => ["a", "b"] Array(1..5) # => [1, 2, 3, 4, 5] Array(key: :value) # => [[:key, :value]] Array(nil) # => [] Array(1) # => [1] Array({:a => "a", :b => "b"}) # => [[:a, "a"], [:b, "b"]]
Method Array.new
:
Array.new # => [] Array.new(3) # => [nil, nil, nil] Array.new(4) {Hash.new} # => [{}, {}, {}, {}] Array.new(3, true) # => [true, true, true]
Note that the last example above populates the array with references to the same object. This is recommended only in cases where that object is a natively immutable object such as a symbol, a numeric, nil
, true
, or false
.
Another way to create an array with various objects, using a block; this usage is safe for mutable objects such as hashes, strings or other arrays:
Array.new(4) {|i| i.to_s } # => ["0", "1", "2", "3"]
Here is a way to create a multi-dimensional array:
Array.new(3) {Array.new(3)} # => [[nil, nil, nil], [nil, nil, nil], [nil, nil, nil]]
A number of Ruby methods, both in the core and in the standard library, provide instance method to_a
, which converts an object to an array.
Gem::List#to_a
Racc::ISet#to_a
In addition to the methods it mixes in through the Enumerable
module, the Array class has proprietary methods for accessing, searching and otherwise manipulating arrays.
Some of the more common ones are illustrated below.
Elements in an array can be retrieved using the Array#[]
method. It can take a single integer argument (a numeric index), a pair of arguments (start and length) or a range. Negative indices start counting from the end, with -1 being the last element.
arr = [1, 2, 3, 4, 5, 6] arr[2] #=> 3 arr[100] #=> nil arr[-3] #=> 4 arr[2, 3] #=> [3, 4, 5] arr[1..4] #=> [2, 3, 4, 5] arr[1..-3] #=> [2, 3, 4]
Another way to access a particular array element is by using the at
method
arr.at(0) #=> 1
The slice
method works in an identical manner to Array#[]
.
To raise an error for indices outside of the array bounds or else to provide a default value when that happens, you can use fetch
.
arr = ['a', 'b', 'c', 'd', 'e', 'f'] arr.fetch(100) #=> IndexError: index 100 outside of array bounds: -6...6 arr.fetch(100, "oops") #=> "oops"
The special methods first
and last
will return the first and last elements of an array, respectively.
arr.first #=> 1 arr.last #=> 6
To return the first n
elements of an array, use take
arr.take(3) #=> [1, 2, 3]
drop
does the opposite of take
, by returning the elements after n
elements have been dropped:
arr.drop(3) #=> [4, 5, 6]
Arrays keep track of their own length at all times. To query an array about the number of elements it contains, use length
, count
or size
.
browsers = ['Chrome', 'Firefox', 'Safari', 'Opera', 'IE'] browsers.length #=> 5 browsers.count #=> 5
To check whether an array contains any elements at all
browsers.empty? #=> false
To check whether a particular item is included in the array
browsers.include?('Konqueror') #=> false
Items can be added to the end of an array by using either push
or <<
arr = [1, 2, 3, 4] arr.push(5) #=> [1, 2, 3, 4, 5] arr << 6 #=> [1, 2, 3, 4, 5, 6]
unshift
will add a new item to the beginning of an array.
arr.unshift(0) #=> [0, 1, 2, 3, 4, 5, 6]
With insert
you can add a new element to an array at any position.
arr.insert(3, 'apple') #=> [0, 1, 2, 'apple', 3, 4, 5, 6]
Using the insert
method, you can also insert multiple values at once:
arr.insert(3, 'orange', 'pear', 'grapefruit') #=> [0, 1, 2, "orange", "pear", "grapefruit", "apple", 3, 4, 5, 6]
The method pop
removes the last element in an array and returns it:
arr = [1, 2, 3, 4, 5, 6] arr.pop #=> 6 arr #=> [1, 2, 3, 4, 5]
To retrieve and at the same time remove the first item, use shift
:
arr.shift #=> 1 arr #=> [2, 3, 4, 5]
To delete an element at a particular index:
arr.delete_at(2) #=> 4 arr #=> [2, 3, 5]
To delete a particular element anywhere in an array, use delete
:
arr = [1, 2, 2, 3] arr.delete(2) #=> 2 arr #=> [1,3]
A useful method if you need to remove nil
values from an array is compact
:
arr = ['foo', 0, nil, 'bar', 7, 'baz', nil] arr.compact #=> ['foo', 0, 'bar', 7, 'baz'] arr #=> ['foo', 0, nil, 'bar', 7, 'baz', nil] arr.compact! #=> ['foo', 0, 'bar', 7, 'baz'] arr #=> ['foo', 0, 'bar', 7, 'baz']
Another common need is to remove duplicate elements from an array.
It has the non-destructive uniq
, and destructive method uniq!
arr = [2, 5, 6, 556, 6, 6, 8, 9, 0, 123, 556] arr.uniq #=> [2, 5, 6, 556, 8, 9, 0, 123]
Like all classes that include the Enumerable
module, Array has an each method, which defines what elements should be iterated over and how. In case of Array’s each
, all elements in the Array instance are yielded to the supplied block in sequence.
Note that this operation leaves the array unchanged.
arr = [1, 2, 3, 4, 5] arr.each {|a| print a -= 10, " "} # prints: -9 -8 -7 -6 -5 #=> [1, 2, 3, 4, 5]
Another sometimes useful iterator is reverse_each
which will iterate over the elements in the array in reverse order.
words = %w[first second third fourth fifth sixth] str = "" words.reverse_each {|word| str += "#{word} "} p str #=> "sixth fifth fourth third second first "
The map
method can be used to create a new array based on the original array, but with the values modified by the supplied block:
arr.map {|a| 2*a} #=> [2, 4, 6, 8, 10] arr #=> [1, 2, 3, 4, 5] arr.map! {|a| a**2} #=> [1, 4, 9, 16, 25] arr #=> [1, 4, 9, 16, 25]
Elements can be selected from an array according to criteria defined in a block. The selection can happen in a destructive or a non-destructive manner. While the destructive operations will modify the array they were called on, the non-destructive methods usually return a new array with the selected elements, but leave the original array unchanged.
arr = [1, 2, 3, 4, 5, 6] arr.select {|a| a > 3} #=> [4, 5, 6] arr.reject {|a| a < 3} #=> [3, 4, 5, 6] arr.drop_while {|a| a < 4} #=> [4, 5, 6] arr #=> [1, 2, 3, 4, 5, 6]
select!
and reject!
are the corresponding destructive methods to select
and reject
Similar to select
vs. reject
, delete_if
and keep_if
have the exact opposite result when supplied with the same block:
arr.delete_if {|a| a < 4} #=> [4, 5, 6] arr #=> [4, 5, 6] arr = [1, 2, 3, 4, 5, 6] arr.keep_if {|a| a < 4} #=> [1, 2, 3] arr #=> [1, 2, 3]
First, what’s elsewhere. Class Array:
Inherits from class Object.
Includes module Enumerable, which provides dozens of additional methods.
Here, class Array provides methods that are useful for:
::[]
: Returns a new array populated with given objects.
::new
: Returns a new array.
::try_convert
: Returns a new array created from a given object.
include?
: Returns whether any element ==
a given object.
empty?
: Returns whether there are no elements.
all?
: Returns whether all elements meet a given criterion.
any?
: Returns whether any element meets a given criterion.
none?
: Returns whether no element ==
a given object.
one?
: Returns whether exactly one element ==
a given object.
count
: Returns the count of elements that meet a given criterion.
find_index
, index
: Returns the index of the first element that meets a given criterion.
rindex
: Returns the index of the last element that meets a given criterion.
hash
: Returns the integer hash code.
<=>
: Returns -1, 0, or 1 * as self
is less than, equal to, or greater than a given object.
==
: Returns whether each element in self
is ==
to the corresponding element in a given object.
eql?
: Returns whether each element in self
is eql?
to the corresponding element in a given object.
These methods do not modify self
.
[]
: Returns one or more elements.
fetch
: Returns the element at a given offset.
first
: Returns one or more leading elements.
last
: Returns one or more trailing elements.
max
: Returns one or more maximum-valued elements, as determined by <=>
or a given block.
min
: Returns one or more minimum-valued elements, as determined by <=>
or a given block.
minmax
: Returns the minimum-valued and maximum-valued elements, as determined by <=>
or a given block.
assoc
: Returns the first element that is an array whose first element ==
a given object.
rassoc
: Returns the first element that is an array whose second element ==
a given object.
at
: Returns the element at a given offset.
values_at
: Returns the elements at given offsets.
dig
: Returns the object in nested objects that is specified by a given index and additional arguments.
drop
: Returns trailing elements as determined by a given index.
take
: Returns leading elements as determined by a given index.
drop_while
: Returns trailing elements as determined by a given block.
take_while
: Returns leading elements as determined by a given block.
slice
: Returns consecutive elements as determined by a given argument.
sort
: Returns all elements in an order determined by <=>
or a given block.
reverse
: Returns all elements in reverse order.
compact
: Returns an array containing all non-nil
elements.
select
, filter
: Returns an array containing elements selected by a given block.
uniq
: Returns an array containing non-duplicate elements.
rotate
: Returns all elements with some rotated from one end to the other.
bsearch
: Returns an element selected via a binary search as determined by a given block.
bsearch_index
: Returns the index of an element selected via a binary search as determined by a given block.
sample
: Returns one or more random elements.
shuffle
: Returns elements in a random order.
These methods add, replace, or reorder elements in self
.
[]=
: Assigns specified elements with a given object.
insert
: Inserts given objects at a given offset; does not replace elements.
concat
: Appends all elements from given arrays.
fill
: Replaces specified elements with specified objects.
replace
: Replaces the content of self
with the content of a given array.
reverse!
: Replaces self
with its elements reversed.
rotate!
: Replaces self
with its elements rotated.
shuffle!
: Replaces self
with its elements in random order.
sort!
: Replaces self
with its elements sorted, as determined by <=>
or a given block.
sort_by!
: Replaces self
with its elements sorted, as determined by a given block.
Each of these methods removes elements from self
:
pop
: Removes and returns the last element.
shift
: Removes and returns the first element.
compact!
: Removes all nil
elements.
delete
: Removes elements equal to a given object.
delete_at
: Removes the element at a given offset.
delete_if
: Removes elements specified by a given block.
keep_if
: Removes elements not specified by a given block.
reject!
: Removes elements specified by a given block.
select!
, filter!
: Removes elements not specified by a given block.
slice!
: Removes and returns a sequence of elements.
uniq!
: Removes duplicates.
&
: Returns an array containing elements found both in self
and a given array.
intersection
: Returns an array containing elements found both in self
and in each given array.
+
: Returns an array containing all elements of self
followed by all elements of a given array.
-
: Returns an array containing all elements of self
that are not found in a given array.
|
: Returns an array containing all elements of self
and all elements of a given array, duplicates removed.
union
: Returns an array containing all elements of self
and all elements of given arrays, duplicates removed.
difference
: Returns an array containing all elements of self
that are not found in any of the given arrays..
product
: Returns or yields all combinations of elements from self
and given arrays.
each
: Passes each element to a given block.
reverse_each
: Passes each element, in reverse order, to a given block.
each_index
: Passes each element index to a given block.
cycle
: Calls a given block with each element, then does so again, for a specified number of times, or forever.
combination
: Calls a given block with combinations of elements of self
; a combination does not use the same element more than once.
permutation
: Calls a given block with permutations of elements of self
; a permutation does not use the same element more than once.
repeated_combination
: Calls a given block with combinations of elements of self
; a combination may use the same element more than once.
repeated_permutation
: Calls a given block with permutations of elements of self
; a permutation may use the same element more than once.
map
, collect
: Returns an array containing the block return-value for each element.
map!
, collect!
: Replaces each element with a block return-value.
flatten
: Returns an array that is a recursive flattening of self
.
flatten!
: Replaces each nested array in self
with the elements from that array.
inspect
, to_s
: Returns a new String
containing the elements.
join
: Returns a newsString containing the elements joined by the field separator.
to_a
: Returns self
or a new array containing all elements.
to_ary
: Returns self
.
to_h
: Returns a new hash formed from the elements.
transpose
: Transposes self
, which must be an array of arrays.
zip
: Returns a new array of arrays containing self
and given arrays; follow the link for details.
*
: Returns one of the following:
With integer argument n
, a new array that is the concatenation of n
copies of self
.
With string argument field_separator
, a new string that is equivalent to join(field_separator)
.
abbrev
: Returns a hash of unambiguous abbreviations for elements.
pack
: Packs the elements into a binary sequence.
sum
: Returns a sum of elements according to either +
or a given block.
Returns an array converted from object
.
Tries to convert object
to an array using to_ary
first and to_a
second:
Array([0, 1, 2]) # => [0, 1, 2] Array({foo: 0, bar: 1}) # => [[:foo, 0], [:bar, 1]] Array(0..4) # => [0, 1, 2, 3, 4]
Returns object
in an array, [object]
, if object
cannot be converted:
Array(:foo) # => [:foo]
Transposes the rows and columns in an Array of Arrays; the nested Arrays must all be the same size:
a = [[:a0, :a1], [:b0, :b1], [:c0, :c1]] a.transpose # => [[:a0, :b0, :c0], [:a1, :b1, :c1]]
Returns the first element in self
that is an Array whose second element ==
obj
:
a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]] a.rassoc(4) # => [2, 4]
Returns nil
if no such element is found.
Related: assoc
.
Returns Ruby object wrapping OLE variant whose variant type is VT_ARRAY. The first argument should be Array
object which specifies dimensions and each size of dimensions of OLE array. The second argument specifies variant type of the element of OLE array.
The following create 2 dimensions OLE array. The first dimensions size is 3, and the second is 4.
ole_ary = WIN32OLE_VARIANT.array([3,4], VT_I4) ruby_ary = ole_ary.value # => [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
Returns a new array populated with the given objects.
Array.[]( 1, 'a', /^A/) # => [1, "a", /^A/] Array[ 1, 'a', /^A/ ] # => [1, "a", /^A/] [ 1, 'a', /^A/ ] # => [1, "a", /^A/]
Returns a new Array.
With no block and no arguments, returns a new empty Array object.
With no block and a single Array argument array
, returns a new Array formed from array
:
a = Array.new([:foo, 'bar', 2]) a.class # => Array a # => [:foo, "bar", 2]
With no block and a single Integer
argument size
, returns a new Array of the given size whose elements are all nil
:
a = Array.new(3) a # => [nil, nil, nil]
With no block and arguments size
and default_value
, returns an Array of the given size; each element is that same default_value
:
a = Array.new(3, 'x') a # => ['x', 'x', 'x']
With a block and argument size
, returns an Array of the given size; the block is called with each successive integer index
; the element for that index
is the return value from the block:
a = Array.new(3) {|index| "Element #{index}" } a # => ["Element 0", "Element 1", "Element 2"]
Raises ArgumentError
if size
is negative.
With a block and no argument, or a single argument 0
, ignores the block and returns a new empty Array.
Returns the new String
formed by calling method #inspect
on each array element:
a = [:foo, 'bar', 2] a.inspect # => "[:foo, \"bar\", 2]"
Returns true
if both array.size == other_array.size
and for each index i
in array
, array[i] == other_array[i]
:
a0 = [:foo, 'bar', 2] a1 = [:foo, 'bar', 2.0] a1 == a0 # => true [] == [] # => true
Otherwise, returns false
.
This method is different from method Array#eql?
, which compares elements using Object#eql?
.
Returns true
if self
and other_array
are the same size, and if, for each index i
in self
, self[i].eql? other_array[i]
:
a0 = [:foo, 'bar', 2] a1 = [:foo, 'bar', 2] a1.eql?(a0) # => true
Otherwise, returns false
.
This method is different from method Array#==
, which compares using method Object#==
.
Returns the integer hash value for self
.
Two arrays with the same content will have the same hash code (and will compare using eql?):
[0, 1, 2].hash == [0, 1, 2].hash # => true [0, 1, 2].hash == [0, 1, 3].hash # => false
Returns elements from self
; does not modify self
.
When a single Integer
argument index
is given, returns the element at offset index
:
a = [:foo, 'bar', 2] a[0] # => :foo a[2] # => 2 a # => [:foo, "bar", 2]
If index
is negative, counts relative to the end of self
:
a = [:foo, 'bar', 2] a[-1] # => 2 a[-2] # => "bar"
If index
is out of range, returns nil
.
When two Integer
arguments start
and length
are given, returns a new Array of size length
containing successive elements beginning at offset start
:
a = [:foo, 'bar', 2] a[0, 2] # => [:foo, "bar"] a[1, 2] # => ["bar", 2]
If start + length
is greater than self.length
, returns all elements from offset start
to the end:
a = [:foo, 'bar', 2] a[0, 4] # => [:foo, "bar", 2] a[1, 3] # => ["bar", 2] a[2, 2] # => [2]
If start == self.size
and length >= 0
, returns a new empty Array.
If length
is negative, returns nil
.
When a single Range
argument range
is given, treats range.min
as start
above and range.size
as length
above:
a = [:foo, 'bar', 2] a[0..1] # => [:foo, "bar"] a[1..2] # => ["bar", 2]
Special case: If range.start == a.size
, returns a new empty Array.
If range.end
is negative, calculates the end index from the end:
a = [:foo, 'bar', 2] a[0..-1] # => [:foo, "bar", 2] a[0..-2] # => [:foo, "bar"] a[0..-3] # => [:foo]
If range.start
is negative, calculates the start index from the end:
a = [:foo, 'bar', 2] a[-1..2] # => [2] a[-2..2] # => ["bar", 2] a[-3..2] # => [:foo, "bar", 2]
If range.start
is larger than the array size, returns nil
.
a = [:foo, 'bar', 2] a[4..1] # => nil a[4..0] # => nil a[4..-1] # => nil
When a single Enumerator::ArithmeticSequence
argument aseq
is given, returns an Array of elements corresponding to the indexes produced by the sequence.
a = ['--', 'data1', '--', 'data2', '--', 'data3'] a[(1..).step(2)] # => ["data1", "data2", "data3"]
Unlike slicing with range, if the start or the end of the arithmetic sequence is larger than array size, throws RangeError
.
a = ['--', 'data1', '--', 'data2', '--', 'data3'] a[(1..11).step(2)] # RangeError (((1..11).step(2)) out of range) a[(7..).step(2)] # RangeError (((7..).step(2)) out of range)
If given a single argument, and its type is not one of the listed, tries to convert it to Integer
, and raises if it is impossible:
a = [:foo, 'bar', 2] # Raises TypeError (no implicit conversion of Symbol into Integer): a[:foo]
Assigns elements in self
; returns the given object
.
When Integer
argument index
is given, assigns object
to an element in self
.
If index
is non-negative, assigns object
the element at offset index
:
a = [:foo, 'bar', 2] a[0] = 'foo' # => "foo" a # => ["foo", "bar", 2]
If index
is greater than self.length
, extends the array:
a = [:foo, 'bar', 2] a[7] = 'foo' # => "foo" a # => [:foo, "bar", 2, nil, nil, nil, nil, "foo"]
If index
is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2] a[-1] = 'two' # => "two" a # => [:foo, "bar", "two"]
When Integer
arguments start
and length
are given and object
is not an Array, removes length - 1
elements beginning at offset start
, and assigns object
at offset start
:
a = [:foo, 'bar', 2] a[0, 2] = 'foo' # => "foo" a # => ["foo", 2]
If start
is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2] a[-2, 2] = 'foo' # => "foo" a # => [:foo, "foo"]
If start
is non-negative and outside the array ( >= self.size
), extends the array with nil
, assigns object
at offset start
, and ignores length
:
a = [:foo, 'bar', 2] a[6, 50] = 'foo' # => "foo" a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
If length
is zero, shifts elements at and following offset start
and assigns object
at offset start
:
a = [:foo, 'bar', 2] a[1, 0] = 'foo' # => "foo" a # => [:foo, "foo", "bar", 2]
If length
is too large for the existing array, does not extend the array:
a = [:foo, 'bar', 2] a[1, 5] = 'foo' # => "foo" a # => [:foo, "foo"]
When Range
argument range
is given and object
is an Array, removes length - 1
elements beginning at offset start
, and assigns object
at offset start
:
a = [:foo, 'bar', 2] a[0..1] = 'foo' # => "foo" a # => ["foo", 2]
if range.begin
is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2] a[-2..2] = 'foo' # => "foo" a # => [:foo, "foo"]
If the array length is less than range.begin
, assigns object
at offset range.begin
, and ignores length
:
a = [:foo, 'bar', 2] a[6..50] = 'foo' # => "foo" a # => [:foo, "bar", 2, nil, nil, nil, "foo"]
If range.end
is zero, shifts elements at and following offset start
and assigns object
at offset start
:
a = [:foo, 'bar', 2] a[1..0] = 'foo' # => "foo" a # => [:foo, "foo", "bar", 2]
If range.end
is negative, assigns object
at offset start
, retains range.end.abs -1
elements past that, and removes those beyond:
a = [:foo, 'bar', 2] a[1..-1] = 'foo' # => "foo" a # => [:foo, "foo"] a = [:foo, 'bar', 2] a[1..-2] = 'foo' # => "foo" a # => [:foo, "foo", 2] a = [:foo, 'bar', 2] a[1..-3] = 'foo' # => "foo" a # => [:foo, "foo", "bar", 2] a = [:foo, 'bar', 2]
If range.end
is too large for the existing array, replaces array elements, but does not extend the array with nil
values:
a = [:foo, 'bar', 2] a[1..5] = 'foo' # => "foo" a # => [:foo, "foo"]
Returns the element at Integer
offset index
; does not modify self
.
a = [:foo, 'bar', 2] a.at(0) # => :foo a.at(2) # => 2
Returns the element at offset index
.
With the single Integer
argument index
, returns the element at offset index
:
a = [:foo, 'bar', 2] a.fetch(1) # => "bar"
If index
is negative, counts from the end of the array:
a = [:foo, 'bar', 2] a.fetch(-1) # => 2 a.fetch(-2) # => "bar"
With arguments index
and default_value
, returns the element at offset index
if index is in range, otherwise returns default_value
:
a = [:foo, 'bar', 2] a.fetch(1, nil) # => "bar"
With argument index
and a block, returns the element at offset index
if index is in range (and the block is not called); otherwise calls the block with index and returns its return value:
a = [:foo, 'bar', 2] a.fetch(1) {|index| raise 'Cannot happen' } # => "bar" a.fetch(50) {|index| "Value for #{index}" } # => "Value for 50"
Adds to array
all elements from each Array in other_arrays
; returns self
:
a = [0, 1] a.concat([2, 3], [4, 5]) # => [0, 1, 2, 3, 4, 5]
Returns a new Array that is the union of self
and all given Arrays other_arrays
; duplicates are removed; order is preserved; items are compared using eql?
:
[0, 1, 2, 3].union([4, 5], [6, 7]) # => [0, 1, 2, 3, 4, 5, 6, 7] [0, 1, 1].union([2, 1], [3, 1]) # => [0, 1, 2, 3] [0, 1, 2, 3].union([3, 2], [1, 0]) # => [0, 1, 2, 3]
Returns a copy of self
if no arguments given.
Related: Array#|
.
Returns a new Array containing only those elements from self
that are not found in any of the Arrays other_arrays
; items are compared using eql?
; order from self
is preserved:
[0, 1, 1, 2, 1, 1, 3, 1, 1].difference([1]) # => [0, 2, 3] [0, 1, 2, 3].difference([3, 0], [1, 3]) # => [2] [0, 1, 2].difference([4]) # => [0, 1, 2]
Returns a copy of self
if no arguments given.
Related: Array#-
.
Returns a new Array containing each element found both in self
and in all of the given Arrays other_arrays
; duplicates are omitted; items are compared using eql?
(items must also implement hash
correctly):
[0, 1, 2, 3].intersection([0, 1, 2], [0, 1, 3]) # => [0, 1] [0, 0, 1, 1, 2, 3].intersection([0, 1, 2], [0, 1, 3]) # => [0, 1]
Preserves order from self
:
[0, 1, 2].intersection([2, 1, 0]) # => [0, 1, 2]
Returns a copy of self
if no arguments given.
Related: Array#&
.
Returns true
if the array and other_ary
have at least one element in common, otherwise returns false
:
a = [ 1, 2, 3 ] b = [ 3, 4, 5 ] c = [ 5, 6, 7 ] a.intersect?(b) #=> true a.intersect?(c) #=> false
Array
elements are compared using eql?
(items must also implement hash
correctly).
Appends object
to self
; returns self
:
a = [:foo, 'bar', 2] a << :baz # => [:foo, "bar", 2, :baz]
Appends object
as one element, even if it is another Array:
a = [:foo, 'bar', 2] a1 = a << [3, 4] a1 # => [:foo, "bar", 2, [3, 4]]
Appends trailing elements.
Appends each argument in objects
to self
; returns self
:
a = [:foo, 'bar', 2] a.push(:baz, :bat) # => [:foo, "bar", 2, :baz, :bat]
Appends each argument as one element, even if it is another Array:
a = [:foo, 'bar', 2] a1 = a.push([:baz, :bat], [:bam, :bad]) a1 # => [:foo, "bar", 2, [:baz, :bat], [:bam, :bad]]