Class

Array

Inheritance
< Object
Included Modules
Enumerable

Arrays are ordered, integer-indexed collections of any object. Array indexing starts at 0, as in C or Java. A negative index is assumed to be relative to the end of the array—that is, an index of -1 indicates the last element of the array, -2 is the next to last element in the array, and so on.

Methods

Class

Visibility Signature
public [] (...)
public new (...)

Instance

Visibility Signature
public & (p1)
public * (p1)
public + (p1)
public - (p1)
public << (p1)
public <=> (p1)
public == (p1)
public [] (...)
public []= (...)
public abbrev (pattern = nil)
public assoc (p1)
public at (p1)
public choice ()
public clear ()
public collect ()
public collect! ()
public combination (p1)
public compact ()
public compact! ()
public concat (p1)
public count (...)
public cycle (...)
public dclone ()
public delete (p1)
public delete_at (p1)
public delete_if ()
public drop (p1)
public drop_while ()
public each ()
public each_index ()
public empty? ()
public eql? (p1)
public fetch (...)
public fill (...)
public find_index (...)
public first (...)
public flatten (...)
public flatten! (...)
public frozen? ()
public hash ()
public include? (p1)
public index (...)
public indexes (...)
public indices (...)
public initialize_copy (p1)
public insert (...)
public inspect ()
public join (...)
public last (...)
public length ()
public map ()
public map! ()
public nitems ()
public pack (p1)
public permutation (...)
public pop (...)
public pretty_print (q)
public pretty_print_cycle (q)
public product (...)
public push (...)
public rassoc (p1)
public reject ()
public reject! ()
public replace (p1)
public reverse ()
public reverse! ()
public reverse_each ()
public rindex (...)
public select ()
public shelljoin ()
public shift (...)
public shuffle ()
public shuffle! ()
public size ()
public slice (...)
public slice! (...)
public sort ()
public sort! ()
public take (p1)
public take_while ()
public to_a ()
public to_ary ()
public to_s ()
public to_yaml ( opts = {} )
public transpose ()
public uniq ()
public uniq! ()
public unshift (...)
public values_at (...)
public yaml_initialize ( tag, val )
public zip (...)
public | (p1)

Class Method Detail

[](...)

Returns a new array populated with the given objects.

  Array.[]( 1, 'a', /^A/ )
  Array[ 1, 'a', /^A/ ]
  [ 1, 'a', /^A/ ]

Array.new(size=0, obj=nil)
Array.new(array)
Array.new(size) {|index| block }

Returns a new array. In the first form, the new array is empty. In the second it is created with size copies of obj (that is, size references to the same obj). The third form creates a copy of the array passed as a parameter (the array is generated by calling to_ary on the parameter). In the last form, an array of the given size is created. Each element in this array is calculated by passing the element‘s index to the given block and storing the return value.

   Array.new
   Array.new(2)
   Array.new(5, "A")

   # only one copy of the object is created
   a = Array.new(2, Hash.new)
   a[0]['cat'] = 'feline'
   a
   a[1]['cat'] = 'Felix'
   a

   # here multiple copies are created
   a = Array.new(2) { Hash.new }
   a[0]['cat'] = 'feline'
   a

   squares = Array.new(5) {|i| i*i}
   squares

   copy = Array.new(squares)

Instance Method Detail

array & other_array

Set Intersection—Returns a new array containing elements common to the two arrays, with no duplicates.

   [ 1, 1, 3, 5 ] & [ 1, 2, 3 ]   #=> [ 1, 3 ]

array * int → an_array
array * str → a_string

Repetition—With a String argument, equivalent to self.join(str). Otherwise, returns a new array built by concatenating the int copies of self.

   [ 1, 2, 3 ] * 3    #=> [ 1, 2, 3, 1, 2, 3, 1, 2, 3 ]
   [ 1, 2, 3 ] * ","  #=> "1,2,3"

array + other_array → an_array

Concatenation—Returns a new array built by concatenating the two arrays together to produce a third array.

   [ 1, 2, 3 ] + [ 4, 5 ]    #=> [ 1, 2, 3, 4, 5 ]

array - other_array → an_array

Array Difference—Returns a new array that is a copy of the original array, removing any items that also appear in other_array. (If you need set-like behavior, see the library class Set.)

   [ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ]  #=>  [ 3, 3, 5 ]

array << obj → array

Append—Pushes the given object on to the end of this array. This expression returns the array itself, so several appends may be chained together.

   [ 1, 2 ] << "c" << "d" << [ 3, 4 ]
           #=>  [ 1, 2, "c", "d", [ 3, 4 ] ]

array <=> other_array → -1, 0, +1

Comparison—Returns an integer (-1, 0, or +1) if this array is less than, equal to, or greater than other_array. Each object in each array is compared (using <=>). If any value isn‘t equal, then that inequality is the return value. If all the values found are equal, then the return is based on a comparison of the array lengths. Thus, two arrays are ``equal’’ according to Array#<=> if and only if they have the same length and the value of each element is equal to the value of the corresponding element in the other array.

   [ "a", "a", "c" ]    <=> [ "a", "b", "c" ]   #=> -1
   [ 1, 2, 3, 4, 5, 6 ] <=> [ 1, 2 ]            #=> +1

array == other_array → bool

Equality—Two arrays are equal if they contain the same number of elements and if each element is equal to (according to Object.==) the corresponding element in the other array.

   [ "a", "c" ]    == [ "a", "c", 7 ]     #=> false
   [ "a", "c", 7 ] == [ "a", "c", 7 ]     #=> true
   [ "a", "c", 7 ] == [ "a", "d", "f" ]   #=> false

array[index] → obj or nil
array[start, length] → an_array or nil
array[range] → an_array or nil
array.slice(index) → obj or nil
array.slice(start, length) → an_array or nil
array.slice(range) → an_array or nil

Element Reference—Returns the element at index, or returns a subarray starting at start and continuing for length elements, or returns a subarray specified by range. Negative indices count backward from the end of the array (-1 is the last element). Returns nil if the index (or starting index) are out of range.

   a = [ "a", "b", "c", "d", "e" ]
   a[2] +  a[0] + a[1]    #=> "cab"
   a[6]                   #=> nil
   a[1, 2]                #=> [ "b", "c" ]
   a[1..3]                #=> [ "b", "c", "d" ]
   a[4..7]                #=> [ "e" ]
   a[6..10]               #=> nil
   a[-3, 3]               #=> [ "c", "d", "e" ]
   # special cases
   a[5]                   #=> nil
   a[5, 1]                #=> []
   a[5..10]               #=> []

array[index] = obj → obj
array[start, length] = obj or an_array or nil → obj or an_array or nil
array[range] = obj or an_array or nil → obj or an_array or nil

Element Assignment—Sets the element at index, or replaces a subarray starting at start and continuing for length elements, or replaces a subarray specified by range. If indices are greater than the current capacity of the array, the array grows automatically. A negative indices will count backward from the end of the array. Inserts elements if length is zero. If nil is used in the second and third form, deletes elements from self. An IndexError is raised if a negative index points past the beginning of the array. See also Array#push, and Array#unshift.

   a = Array.new
   a[4] = "4";                 #=> [nil, nil, nil, nil, "4"]
   a[0, 3] = [ 'a', 'b', 'c' ] #=> ["a", "b", "c", nil, "4"]
   a[1..2] = [ 1, 2 ]          #=> ["a", 1, 2, nil, "4"]
   a[0, 2] = "?"               #=> ["?", 2, nil, "4"]
   a[0..2] = "A"               #=> ["A", "4"]
   a[-1]   = "Z"               #=> ["A", "Z"]
   a[1..-1] = nil              #=> ["A"]

abbrev(pattern = nil)

Calculates the set of unambiguous abbreviations for the strings in self. If passed a pattern or a string, only the strings matching the pattern or starting with the string are considered.

  %w{ car cone }.abbrev   #=> { "ca" => "car", "car" => "car",
                                "co" => "cone", "con" => cone",
                                "cone" => "cone" }

array.assoc(obj) → an_array or nil

Searches through an array whose elements are also arrays comparing obj with the first element of each contained array using obj.==. Returns the first contained array that matches (that is, the first associated array), or nil if no match is found. See also Array#rassoc.

   s1 = [ "colors", "red", "blue", "green" ]
   s2 = [ "letters", "a", "b", "c" ]
   s3 = "foo"
   a  = [ s1, s2, s3 ]
   a.assoc("letters")  #=> [ "letters", "a", "b", "c" ]
   a.assoc("foo")      #=> nil

array.at(index) → obj or nil

Returns the element at index. A negative index counts from the end of self. Returns nil if the index is out of range. See also Array#[]. (Array#at is slightly faster than Array#[], as it does not accept ranges and so on.)

   a = [ "a", "b", "c", "d", "e" ]
   a.at(0)     #=> "a"
   a.at(-1)    #=> "e"

array.choice → obj

Choose a random element from an array.

array.clear → array

Removes all elements from self.

   a = [ "a", "b", "c", "d", "e" ]
   a.clear    #=> [ ]

array.collect {|item| block } → an_array
array.map {|item| block } → an_array

Invokes block once for each element of self. Creates a new array containing the values returned by the block. See also Enumerable#collect.

   a = [ "a", "b", "c", "d" ]
   a.collect {|x| x + "!" }   #=> ["a!", "b!", "c!", "d!"]
   a                          #=> ["a", "b", "c", "d"]

array.collect! {|item| block } → array
array.map! {|item| block } → array

Invokes the block once for each element of self, replacing the element with the value returned by block. See also Enumerable#collect.

   a = [ "a", "b", "c", "d" ]
   a.collect! {|x| x + "!" }
   a             #=>  [ "a!", "b!", "c!", "d!" ]

ary.combination(n) { |c| block } → ary
ary.combination(n) → enumerator

When invoked with a block, yields all combinations of length n of elements from ary and then returns ary itself. The implementation makes no guarantees about the order in which the combinations are yielded.

When invoked without a block, returns an enumerator object instead.

Examples:

    a = [1, 2, 3, 4]
    a.combination(1).to_a  #=> [[1],[2],[3],[4]]
    a.combination(2).to_a  #=> [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
    a.combination(3).to_a  #=> [[1,2,3],[1,2,4],[1,3,4],[2,3,4]]
    a.combination(4).to_a  #=> [[1,2,3,4]]
    a.combination(0).to_a  #=> [[]] # one combination of length 0
    a.combination(5).to_a  #=> []   # no combinations of length 5

array.compact → an_array

Returns a copy of self with all nil elements removed.

   [ "a", nil, "b", nil, "c", nil ].compact
                     #=> [ "a", "b", "c" ]

array.compact! → array or nil

Removes nil elements from array. Returns nil if no changes were made.

   [ "a", nil, "b", nil, "c" ].compact! #=> [ "a", "b", "c" ]
   [ "a", "b", "c" ].compact!           #=> nil

array.concat(other_array) → array

Appends the elements in other_array to self.

   [ "a", "b" ].concat( ["c", "d"] ) #=> [ "a", "b", "c", "d" ]

array.count → int
array.count(obj) → int
array.count { |item| block } → int

Returns the number of elements. If an argument is given, counts the number of elements which equals to obj. If a block is given, counts the number of elements yielding a true value.

   ary = [1, 2, 4, 2]
   ary.count             # => 4
   ary.count(2)          # => 2
   ary.count{|x|x%2==0}  # => 3

ary.cycle {|obj| block }
ary.cycle(n) {|obj| block }

Calls block for each element repeatedly n times or forever if none or nil is given. If a non-positive number is given or the array is empty, does nothing. Returns nil if the loop has finished without getting interrupted.

   a = ["a", "b", "c"]
   a.cycle {|x| puts x }  # print, a, b, c, a, b, c,.. forever.
   a.cycle(2) {|x| puts x }  # print, a, b, c, a, b, c.

dclone()

array.delete(obj) → obj or nil
array.delete(obj) { block } → obj or nil

Deletes items from self that are equal to obj. If the item is not found, returns nil. If the optional code block is given, returns the result of block if the item is not found.

   a = [ "a", "b", "b", "b", "c" ]
   a.delete("b")                   #=> "b"
   a                               #=> ["a", "c"]
   a.delete("z")                   #=> nil
   a.delete("z") { "not found" }   #=> "not found"

array.delete_at(index) → obj or nil

Deletes the element at the specified index, returning that element, or nil if the index is out of range. See also Array#slice!.

   a = %w( ant bat cat dog )
   a.delete_at(2)    #=> "cat"
   a                 #=> ["ant", "bat", "dog"]
   a.delete_at(99)   #=> nil

array.delete_if {|item| block } → array

Deletes every element of self for which block evaluates to true.

   a = [ "a", "b", "c" ]
   a.delete_if {|x| x >= "b" }   #=> ["a"]

ary.drop(n) => array

Drops first n elements from ary, and returns rest elements in an array.

   a = [1, 2, 3, 4, 5, 0]
   a.drop(3)             # => [4, 5, 0]

ary.drop_while {|arr| block } => array

Drops elements up to, but not including, the first element for which the block returns nil or false and returns an array containing the remaining elements.

   a = [1, 2, 3, 4, 5, 0]
   a.drop_while {|i| i < 3 }   # => [3, 4, 5, 0]

array.each {|item| block } → array

Calls block once for each element in self, passing that element as a parameter.

   a = [ "a", "b", "c" ]
   a.each {|x| print x, " -- " }

produces:

   a -- b -- c --

array.each_index {|index| block } → array

Same as Array#each, but passes the index of the element instead of the element itself.

   a = [ "a", "b", "c" ]
   a.each_index {|x| print x, " -- " }

produces:

   0 -- 1 -- 2 --

array.empty? → true or false

Returns true if self array contains no elements.

   [].empty?   #=> true

array.eql?(other) → true or false

Returns true if array and other are the same object, or are both arrays with the same content.

array.fetch(index) → obj
array.fetch(index, default ) → obj
array.fetch(index) {|index| block } → obj

Tries to return the element at position index. If the index lies outside the array, the first form throws an IndexError exception, the second form returns default, and the third form returns the value of invoking the block, passing in the index. Negative values of index count from the end of the array.

   a = [ 11, 22, 33, 44 ]
   a.fetch(1)               #=> 22
   a.fetch(-1)              #=> 44
   a.fetch(4, 'cat')        #=> "cat"
   a.fetch(4) { |i| i*i }   #=> 16

array.fill(obj) → array
array.fill(obj, start [, length]) → array
array.fill(obj, range ) → array
array.fill {|index| block } → array
array.fill(start [, length] ) {|index| block } → array
array.fill(range) {|index| block } → array

The first three forms set the selected elements of self (which may be the entire array) to obj. A start of nil is equivalent to zero. A length of nil is equivalent to self.length. The last three forms fill the array with the value of the block. The block is passed the absolute index of each element to be filled.

   a = [ "a", "b", "c", "d" ]
   a.fill("x")              #=> ["x", "x", "x", "x"]
   a.fill("z", 2, 2)        #=> ["x", "x", "z", "z"]
   a.fill("y", 0..1)        #=> ["y", "y", "z", "z"]
   a.fill {|i| i*i}         #=> [0, 1, 4, 9]
   a.fill(-2) {|i| i*i*i}   #=> [0, 1, 8, 27]

array.index(obj) → int or nil
array.index {|item| block} → int or nil

Returns the index of the first object in self such that is == to obj. If a block is given instead of an argument, returns first object for which block is true. Returns nil if no match is found.

   a = [ "a", "b", "c" ]
   a.index("b")        #=> 1
   a.index("z")        #=> nil
   a.index{|x|x=="b"}  #=> 1

This is an alias of find_index.

array.first → obj or nil
array.first(n) → an_array

Returns the first element, or the first n elements, of the array. If the array is empty, the first form returns nil, and the second form returns an empty array.

   a = [ "q", "r", "s", "t" ]
   a.first    #=> "q"
   a.first(1) #=> ["q"]
   a.first(3) #=> ["q", "r", "s"]

array.flatten → an_array
array.flatten(level) → an_array

Returns a new array that is a one-dimensional flattening of this array (recursively). That is, for every element that is an array, extract its elements into the new array. If the optional level argument determines the level of recursion to flatten.

   s = [ 1, 2, 3 ]           #=> [1, 2, 3]
   t = [ 4, 5, 6, [7, 8] ]   #=> [4, 5, 6, [7, 8]]
   a = [ s, t, 9, 10 ]       #=> [[1, 2, 3], [4, 5, 6, [7, 8]], 9, 10]
   a.flatten                 #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   a = [ 1, 2, [3, [4, 5] ] ]
   a.flatten(1)              #=> [1, 2, 3, [4, 5]]

array.flatten! → array or nil
array.flatten!(level) → array or nil

Flattens self in place. Returns nil if no modifications were made (i.e., array contains no subarrays.) If the optional level argument determines the level of recursion to flatten.

   a = [ 1, 2, [3, [4, 5] ] ]
   a.flatten!   #=> [1, 2, 3, 4, 5]
   a.flatten!   #=> nil
   a            #=> [1, 2, 3, 4, 5]
   a = [ 1, 2, [3, [4, 5] ] ]
   a.flatten!(1) #=> [1, 2, 3, [4, 5]]

array.frozen? → true or false

Return true if this array is frozen (or temporarily frozen while being sorted).

array.hash → fixnum

Compute a hash-code for this array. Two arrays with the same content will have the same hash code (and will compare using eql?).

array.include?(obj) → true or false

Returns true if the given object is present in self (that is, if any object == anObject), false otherwise.

   a = [ "a", "b", "c" ]
   a.include?("b")   #=> true
   a.include?("z")   #=> false

array.index(obj) → int or nil
array.index {|item| block} → int or nil

Returns the index of the first object in self such that is == to obj. If a block is given instead of an argument, returns first object for which block is true. Returns nil if no match is found.

   a = [ "a", "b", "c" ]
   a.index("b")        #=> 1
   a.index("z")        #=> nil
   a.index{|x|x=="b"}  #=> 1

This is an alias of find_index.

array.indexes( i1, i2, ... iN ) → an_array
array.indices( i1, i2, ... iN ) → an_array

Deprecated; use Array#values_at.

array.indexes( i1, i2, ... iN ) → an_array
array.indices( i1, i2, ... iN ) → an_array

Deprecated; use Array#values_at.

array.replace(other_array) → array

Replaces the contents of self with the contents of other_array, truncating or expanding if necessary.

   a = [ "a", "b", "c", "d", "e" ]
   a.replace([ "x", "y", "z" ])   #=> ["x", "y", "z"]
   a                              #=> ["x", "y", "z"]

array.insert(index, obj...) → array

Inserts the given values before the element with the given index (which may be negative).

   a = %w{ a b c d }
   a.insert(2, 99)         #=> ["a", "b", 99, "c", "d"]
   a.insert(-2, 1, 2, 3)   #=> ["a", "b", 99, "c", 1, 2, 3, "d"]

array.inspect → string

Create a printable version of array.

array.join(sep=$,) → str

Returns a string created by converting each element of the array to a string, separated by sep.

   [ "a", "b", "c" ].join        #=> "abc"
   [ "a", "b", "c" ].join("-")   #=> "a-b-c"

array.last → obj or nil
array.last(n) → an_array

Returns the last element(s) of self. If the array is empty, the first form returns nil.

   [ "w", "x", "y", "z" ].last   #=> "z"

array.length → int

Returns the number of elements in self. May be zero.

   [ 1, 2, 3, 4, 5 ].length   #=> 5

array.collect {|item| block } → an_array
array.map {|item| block } → an_array

Invokes block once for each element of self. Creates a new array containing the values returned by the block. See also Enumerable#collect.

   a = [ "a", "b", "c", "d" ]
   a.collect {|x| x + "!" }   #=> ["a!", "b!", "c!", "d!"]
   a                          #=> ["a", "b", "c", "d"]

array.collect! {|item| block } → array
array.map! {|item| block } → array

Invokes the block once for each element of self, replacing the element with the value returned by block. See also Enumerable#collect.

   a = [ "a", "b", "c", "d" ]
   a.collect! {|x| x + "!" }
   a             #=>  [ "a!", "b!", "c!", "d!" ]

array.nitems → int

Returns the number of non-nil elements in self.

May be zero.

   [ 1, nil, 3, nil, 5 ].nitems   #=> 3

arr.pack ( aTemplateString ) → aBinaryString

Packs the contents of arr into a binary sequence according to the directives in aTemplateString (see the table below) Directives ``A,’’ ``a,’’ and ``Z’’ may be followed by a count, which gives the width of the resulting field. The remaining directives also may take a count, indicating the number of array elements to convert. If the count is an asterisk (``*’’), all remaining array elements will be converted. Any of the directives ``sSiIlL’’ may be followed by an underscore (``_’’) to use the underlying platform‘s native size for the specified type; otherwise, they use a platform-independent size. Spaces are ignored in the template string. See also String#unpack.

   a = [ "a", "b", "c" ]
   n = [ 65, 66, 67 ]
   a.pack("A3A3A3")   #=> "a  b  c  "
   a.pack("a3a3a3")   #=> "a\000\000b\000\000c\000\000"
   n.pack("ccc")      #=> "ABC"

Directives for pack.

 Directive    Meaning
 ---------------------------------------------------------------
     @     |  Moves to absolute position
     A     |  ASCII string (space padded, count is width)
     a     |  ASCII string (null padded, count is width)
     B     |  Bit string (descending bit order)
     b     |  Bit string (ascending bit order)
     C     |  Unsigned char
     c     |  Char
     D, d  |  Double-precision float, native format
     E     |  Double-precision float, little-endian byte order
     e     |  Single-precision float, little-endian byte order
     F, f  |  Single-precision float, native format
     G     |  Double-precision float, network (big-endian) byte order
     g     |  Single-precision float, network (big-endian) byte order
     H     |  Hex string (high nibble first)
     h     |  Hex string (low nibble first)
     I     |  Unsigned integer
     i     |  Integer
     L     |  Unsigned long
     l     |  Long
     M     |  Quoted printable, MIME encoding (see RFC2045)
     m     |  Base64 encoded string
     N     |  Long, network (big-endian) byte order
     n     |  Short, network (big-endian) byte-order
     P     |  Pointer to a structure (fixed-length string)
     p     |  Pointer to a null-terminated string
     Q, q  |  64-bit number
     S     |  Unsigned short
     s     |  Short
     U     |  UTF-8
     u     |  UU-encoded string
     V     |  Long, little-endian byte order
     v     |  Short, little-endian byte order
     w     |  BER-compressed integer\fnm
     X     |  Back up a byte
     x     |  Null byte
     Z     |  Same as ``a'', except that null is added with *

ary.permutation { |p| block } → array
ary.permutation → enumerator
ary.permutation(n) { |p| block } → array
ary.permutation(n) → enumerator

When invoked with a block, yield all permutations of length n of the elements of ary, then return the array itself. If n is not specified, yield all permutations of all elements. The implementation makes no guarantees about the order in which the permutations are yielded.

When invoked without a block, return an enumerator object instead.

Examples:

    a = [1, 2, 3]
    a.permutation.to_a     #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
    a.permutation(1).to_a  #=> [[1],[2],[3]]
    a.permutation(2).to_a  #=> [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]]
    a.permutation(3).to_a  #=> [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
    a.permutation(0).to_a  #=> [[]] # one permutation of length 0
    a.permutation(4).to_a  #=> []   # no permutations of length 4

array.pop → obj or nil
array.pop(n) → array

Removes the last element from self and returns it, or nil if the array is empty.

If a number n is given, returns an array of the last n elements (or less) just like array.slice!(-n, n) does.

   a = [ "a", "b", "c", "d" ]
   a.pop     #=> "d"
   a.pop(2)  #=> ["b", "c"]
   a         #=> ["a"]

pretty_print(q)

pretty_print_cycle(q)

ary.product(other_ary, ...)

Returns an array of all combinations of elements from all arrays. The length of the returned array is the product of the length of ary and the argument arrays

   [1,2,3].product([4,5])     # => [[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]]
   [1,2].product([1,2])       # => [[1,1],[1,2],[2,1],[2,2]]
   [1,2].product([3,4],[5,6]) # => [[1,3,5],[1,3,6],[1,4,5],[1,4,6],
                              #     [2,3,5],[2,3,6],[2,4,5],[2,4,6]]
   [1,2].product()            # => [[1],[2]]
   [1,2].product([])          # => []

array.push(obj, ... ) → array

Append—Pushes the given object(s) on to the end of this array. This expression returns the array itself, so several appends may be chained together.

   a = [ "a", "b", "c" ]
   a.push("d", "e", "f")
           #=> ["a", "b", "c", "d", "e", "f"]

array.rassoc(key) → an_array or nil

Searches through the array whose elements are also arrays. Compares key with the second element of each contained array using ==. Returns the first contained array that matches. See also Array#assoc.

   a = [ [ 1, "one"], [2, "two"], [3, "three"], ["ii", "two"] ]
   a.rassoc("two")    #=> [2, "two"]
   a.rassoc("four")   #=> nil

array.reject {|item| block } → an_array

Returns a new array containing the items in self for which the block is not true.

array.reject! {|item| block } → array or nil

Equivalent to Array#delete_if, deleting elements from self for which the block evaluates to true, but returns nil if no changes were made. Also see Enumerable#reject.

array.replace(other_array) → array

Replaces the contents of self with the contents of other_array, truncating or expanding if necessary.

   a = [ "a", "b", "c", "d", "e" ]
   a.replace([ "x", "y", "z" ])   #=> ["x", "y", "z"]
   a                              #=> ["x", "y", "z"]

array.reverse → an_array

Returns a new array containing self‘s elements in reverse order.

   [ "a", "b", "c" ].reverse   #=> ["c", "b", "a"]
   [ 1 ].reverse               #=> [1]

array.reverse! → array

Reverses self in place.

   a = [ "a", "b", "c" ]
   a.reverse!       #=> ["c", "b", "a"]
   a                #=> ["c", "b", "a"]

array.reverse_each {|item| block }

Same as Array#each, but traverses self in reverse order.

   a = [ "a", "b", "c" ]
   a.reverse_each {|x| print x, " " }

produces:

   c b a

array.rindex(obj) → int or nil

Returns the index of the last object in array == to obj. If a block is given instead of an argument, returns first object for which block is true. Returns nil if no match is found.

   a = [ "a", "b", "b", "b", "c" ]
   a.rindex("b")        #=> 3
   a.rindex("z")        #=> nil
   a.rindex{|x|x=="b"}  #=> 3

array.select {|item| block } → an_array

Invokes the block passing in successive elements from array, returning an array containing those elements for which the block returns a true value (equivalent to Enumerable#select).

   a = %w{ a b c d e f }
   a.select {|v| v =~ /[aeiou]/}   #=> ["a", "e"]

array.shelljoin => string

Builds a command line string from an argument list array joining all elements escaped for Bourne shell and separated by a space. See +Shellwords::shelljoin+ for details.

array.shift → obj or nil
array.shift(n) → array

Returns the first element of self and removes it (shifting all other elements down by one). Returns nil if the array is empty.

If a number n is given, returns an array of the first n elements (or less) just like array.slice!(0, n) does.

   args = [ "-m", "-q", "filename" ]
   args.shift     #=> "-m"
   args           #=> ["-q", "filename"]

   args = [ "-m", "-q", "filename" ]
   args.shift(2)  #=> ["-m", "-q"]
   args           #=> ["filename"]

array.shuffle → an_array

Returns a new array with elements of this array shuffled.

   a = [ 1, 2, 3 ]           #=> [1, 2, 3]
   a.shuffle                 #=> [2, 3, 1]

array.shuffle! → array or nil

Shuffles elements in self in place.

size()

Alias for length

array[index] → obj or nil
array[start, length] → an_array or nil
array[range] → an_array or nil
array.slice(index) → obj or nil
array.slice(start, length) → an_array or nil
array.slice(range) → an_array or nil

Element Reference—Returns the element at index, or returns a subarray starting at start and continuing for length elements, or returns a subarray specified by range. Negative indices count backward from the end of the array (-1 is the last element). Returns nil if the index (or starting index) are out of range.

   a = [ "a", "b", "c", "d", "e" ]
   a[2] +  a[0] + a[1]    #=> "cab"
   a[6]                   #=> nil
   a[1, 2]                #=> [ "b", "c" ]
   a[1..3]                #=> [ "b", "c", "d" ]
   a[4..7]                #=> [ "e" ]
   a[6..10]               #=> nil
   a[-3, 3]               #=> [ "c", "d", "e" ]
   # special cases
   a[5]                   #=> nil
   a[5, 1]                #=> []
   a[5..10]               #=> []

array.slice!(index) → obj or nil
array.slice!(start, length) → sub_array or nil
array.slice!(range) → sub_array or nil

Deletes the element(s) given by an index (optionally with a length) or by a range. Returns the deleted object, subarray, or nil if the index is out of range. Equivalent to:

   def slice!(*args)
     result = self[*args]
     self[*args] = nil
     result
   end

   a = [ "a", "b", "c" ]
   a.slice!(1)     #=> "b"
   a               #=> ["a", "c"]
   a.slice!(-1)    #=> "c"
   a               #=> ["a"]
   a.slice!(100)   #=> nil
   a               #=> ["a"]

array.sort → an_array
array.sort {| a,b | block } → an_array

Returns a new array created by sorting self. Comparisons for the sort will be done using the <=> operator or using an optional code block. The block implements a comparison between a and b, returning -1, 0, or +1. See also Enumerable#sort_by.

   a = [ "d", "a", "e", "c", "b" ]
   a.sort                    #=> ["a", "b", "c", "d", "e"]
   a.sort {|x,y| y <=> x }   #=> ["e", "d", "c", "b", "a"]

array.sort! → array
array.sort! {| a,b | block } → array

Sorts self. Comparisons for the sort will be done using the <=> operator or using an optional code block. The block implements a comparison between a and b, returning -1, 0, or +1. See also Enumerable#sort_by.

   a = [ "d", "a", "e", "c", "b" ]
   a.sort                    #=> ["a", "b", "c", "d", "e"]
   a.sort {|x,y| y <=> x }   #=> ["e", "d", "c", "b", "a"]

ary.take(n) => array

Returns first n elements from ary.

   a = [1, 2, 3, 4, 5, 0]
   a.take(3)             # => [1, 2, 3]

ary.take_while {|arr| block } => array

Passes elements to the block until the block returns nil or false, then stops iterating and returns an array of all prior elements.

   a = [1, 2, 3, 4, 5, 0]
   a.take_while {|i| i < 3 }   # => [1, 2]

array.to_a → array

Returns self. If called on a subclass of Array, converts the receiver to an Array object.

array.to_ary → array

Returns self.

array.to_s → string

Returns self.join.

   [ "a", "e", "i", "o" ].to_s   #=> "aeio"

to_yaml( opts = {} )

array.transpose → an_array

Assumes that self is an array of arrays and transposes the rows and columns.

   a = [[1,2], [3,4], [5,6]]
   a.transpose   #=> [[1, 3, 5], [2, 4, 6]]

array.uniq → an_array

Returns a new array by removing duplicate values in self.

   a = [ "a", "a", "b", "b", "c" ]
   a.uniq   #=> ["a", "b", "c"]

array.uniq! → array or nil

Removes duplicate elements from self. Returns nil if no changes are made (that is, no duplicates are found).

   a = [ "a", "a", "b", "b", "c" ]
   a.uniq!   #=> ["a", "b", "c"]
   b = [ "a", "b", "c" ]
   b.uniq!   #=> nil

array.unshift(obj, ...) → array

Prepends objects to the front of array. other elements up one.

   a = [ "b", "c", "d" ]
   a.unshift("a")   #=> ["a", "b", "c", "d"]
   a.unshift(1, 2)  #=> [ 1, 2, "a", "b", "c", "d"]

array.values_at(selector,... ) → an_array

Returns an array containing the elements in self corresponding to the given selector(s). The selectors may be either integer indices or ranges. See also Array#select.

   a = %w{ a b c d e f }
   a.values_at(1, 3, 5)
   a.values_at(1, 3, 5, 7)
   a.values_at(-1, -3, -5, -7)
   a.values_at(1..3, 2...5)

yaml_initialize( tag, val )

array.zip(arg, ...) → an_array
array.zip(arg, ...) {| arr | block } → nil

Converts any arguments to arrays, then merges elements of self with corresponding elements from each argument. This generates a sequence of self.size n-element arrays, where n is one more that the count of arguments. If the size of any argument is less than enumObj.size, nil values are supplied. If a block given, it is invoked for each output array, otherwise an array of arrays is returned.

   a = [ 4, 5, 6 ]
   b = [ 7, 8, 9 ]

   [1,2,3].zip(a, b)      #=> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
   [1,2].zip(a,b)         #=> [[1, 4, 7], [2, 5, 8]]
   a.zip([1,2],[8])       #=> [[4,1,8], [5,2,nil], [6,nil,nil]]

array | other_array → an_array

Set Union—Returns a new array by joining this array with other_array, removing duplicates.

   [ "a", "b", "c" ] | [ "c", "d", "a" ]
          #=> [ "a", "b", "c", "d" ]