Returns a new array formed from self with elements rotated from one end to the other.
With non-negative numeric count, rotates elements from the beginning to the end:
[0, 1, 2, 3].rotate(2) # => [2, 3, 0, 1] [0, 1, 2, 3].rotate(2.1) # => [2, 3, 0, 1]
If count is large, uses count % array.size as the count:
[0, 1, 2, 3].rotate(22) # => [2, 3, 0, 1]
With a count of zero, rotates no elements:
[0, 1, 2, 3].rotate(0) # => [0, 1, 2, 3]
With negative numeric count, rotates in the opposite direction, from the end to the beginning:
[0, 1, 2, 3].rotate(-1) # => [3, 0, 1, 2]
If count is small (far from zero), uses count % array.size as the count:
[0, 1, 2, 3].rotate(-21) # => [3, 0, 1, 2]
Related: see Methods for Fetching.
Rotates self in place by moving elements from one end to the other; returns self.
With non-negative numeric count, rotates count elements from the beginning to the end:
[0, 1, 2, 3].rotate!(2) # => [2, 3, 0, 1] [0, 1, 2, 3].rotate!(2.1) # => [2, 3, 0, 1]
If count is large, uses count % array.size as the count:
[0, 1, 2, 3].rotate!(21) # => [1, 2, 3, 0]
If count is zero, rotates no elements:
[0, 1, 2, 3].rotate!(0) # => [0, 1, 2, 3]
With a negative numeric count, rotates in the opposite direction, from end to beginning:
[0, 1, 2, 3].rotate!(-1) # => [3, 0, 1, 2]
If count is small (far from zero), uses count % array.size as the count:
[0, 1, 2, 3].rotate!(-21) # => [3, 0, 1, 2]
Related: see Methods for Assigning.
Returns a new array containing only the non-nil elements from self; element order is preserved:
a = [nil, 0, nil, false, nil, '', nil, [], nil, {}] a.compact # => [0, false, "", [], {}]
Related: Array#compact!; see also Methods for Deleting.
Removes all nil elements from self; Returns self if any elements are removed, nil otherwise:
a = [nil, 0, nil, false, nil, '', nil, [], nil, {}] a.compact! # => [0, false, "", [], {}] a # => [0, false, "", [], {}] a.compact! # => nil
Related: Array#compact; see also Methods for Deleting.
Returns a new array that is a recursive flattening of self to depth levels of recursion; depth must be an integer-convertible object or nil. At each level of recursion:
Each element that is an array is “flattened” (that is, replaced by its individual array elements).
Each element that is not an array is unchanged (even if the element is an object that has instance method flatten).
With non-negative integer argument depth, flattens recursively through depth levels:
a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ] a # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>] a.flatten(0) # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>] a.flatten(1 ) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.flatten(1.1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.flatten(2) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.flatten(3) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
With nil or negative depth, flattens all levels.
a.flatten # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.flatten(-1) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
Related: Array#flatten!; see also Methods for Converting.
Returns self as a recursively flattening of self to depth levels of recursion; depth must be an integer-convertible object, or nil. At each level of recursion:
Each element that is an array is “flattened” (that is, replaced by its individual array elements).
Each element that is not an array is unchanged (even if the element is an object that has instance method flatten).
Returns nil if no elements were flattened.
With non-negative integer argument depth, flattens recursively through depth levels:
a = [ 0, [ 1, [2, 3], 4 ], 5, {foo: 0}, Set.new([6, 7]) ] a # => [0, [1, [2, 3], 4], 5, {:foo=>0}, #<Set: {6, 7}>] a.dup.flatten!(1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.dup.flatten!(1.1) # => [0, 1, [2, 3], 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.dup.flatten!(2) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.dup.flatten!(3) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
With nil or negative argument depth, flattens all levels:
a.dup.flatten! # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>] a.dup.flatten!(-1) # => [0, 1, 2, 3, 4, 5, {:foo=>0}, #<Set: {6, 7}>]
Related: Array#flatten; see also Methods for Assigning.
Iterates over permutations of the elements of self; the order of permutations is indeterminate.
With a block and an in-range positive integer argument count (0 < count <= self.size) given, calls the block with each permutation of self of size count; returns self:
a = [0, 1, 2] perms = [] a.permutation(1) {|perm| perms.push(perm) } perms # => [[0], [1], [2]] perms = [] a.permutation(2) {|perm| perms.push(perm) } perms # => [[0, 1], [0, 2], [1, 0], [1, 2], [2, 0], [2, 1]] perms = [] a.permutation(3) {|perm| perms.push(perm) } perms # => [[0, 1, 2], [0, 2, 1], [1, 0, 2], [1, 2, 0], [2, 0, 1], [2, 1, 0]]
When count is zero, calls the block once with a new empty array:
perms = [] a.permutation(0) {|perm| perms.push(perm) } perms # => [[]]
When count is out of range (negative or larger than self.size), does not call the block:
a.permutation(-1) {|permutation| fail 'Cannot happen' } a.permutation(4) {|permutation| fail 'Cannot happen' }
With no block given, returns a new Enumerator.
Related: Methods for Iterating.
Returns random elements from self, as selected by the object given by the keyword argument random.
With no argument count given, returns one random element from self:
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] a.sample # => 3 a.sample # => 8
Returns nil if self is empty:
[].sample # => nil
With a non-negative numeric argument count given, returns a new array containing count random elements from self:
a.sample(3) # => [8, 9, 2] a.sample(6) # => [9, 6, 0, 3, 1, 4]
The order of the result array is unrelated to the order of self.
Returns a new empty Array if self is empty:
[].sample(4) # => []
May return duplicates in self:
a = [1, 1, 1, 2, 2, 3] a.sample(a.size) # => [1, 1, 3, 2, 1, 2]
Returns no more than a.size elements (because no new duplicates are introduced):
a.sample(50) # => [6, 4, 1, 8, 5, 9, 0, 2, 3, 7]
The object given with the keyword argument random is used as the random number generator:
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] a.sample(random: Random.new(1)) # => 6 a.sample(4, random: Random.new(1)) # => [6, 10, 9, 2]
Related: see Methods for Fetching.
Formats each element in self into a binary string; returns that string. See Packed Data.
Returns a Hash containing implementation-dependent counters inside the VM.
This hash includes information about method/constant caches:
{
:constant_cache_invalidations=>2,
:constant_cache_misses=>14,
:global_cvar_state=>27
}
If USE_DEBUG_COUNTER is enabled, debug counters will be included.
The contents of the hash are implementation specific and may be changed in the future.
This method is only expected to work on C Ruby.
Returns self truncated (toward zero) to a precision of ndigits decimal digits.
When ndigits is negative, the returned value has at least ndigits.abs trailing zeros:
555.truncate(-1) # => 550 555.truncate(-2) # => 500 -555.truncate(-2) # => -500
Returns self when ndigits is zero or positive.
555.truncate # => 555 555.truncate(50) # => 555
Related: Integer#round.
Calls the given block self times with each integer in (0..self-1):
a = [] 5.times {|i| a.push(i) } # => 5 a # => [0, 1, 2, 3, 4]
With no block given, returns an Enumerator.
Returns the imaginary value for self:
Complex.rect(7).imag # => 0 Complex.rect(9, -4).imag # => -4
If self was created with polar coordinates, the returned value is computed, and may be inexact:
Complex.polar(1, Math::PI/4).imag # => 0.7071067811865476 # Square root of 2.
Returns the conjugate of self, Complex.rect(self.imag, self.real):
Complex.rect(1, 2).conj # => (1-2i)
Returns self truncated (toward zero) to a precision of digits decimal digits.
Numeric implements this by converting self to a Float and invoking Float#truncate.
Returns true if self is less than 0, false otherwise.
Returns zero.
Returns self.
Extracts data from self.
If block is not given, forming objects that become the elements of a new array, and returns that array. Otherwise, yields each object.
See Packed Data.
Like String#unpack, but unpacks and returns only the first extracted object. See Packed Data.
Returns the count of characters (not bytes) in self:
'foo'.length # => 3 'тест'.length # => 4 'こんにちは'.length # => 5
Contrast with String#bytesize:
'foo'.bytesize # => 3 'тест'.bytesize # => 8 'こんにちは'.bytesize # => 15
Returns a MatchData object (or nil) based on self and the given pattern.
Note: also updates Global Variables at Regexp.
Computes regexp by converting pattern (if not already a Regexp).
regexp = Regexp.new(pattern)
Computes matchdata, which will be either a MatchData object or nil (see Regexp#match):
matchdata = <tt>regexp.match(self)
With no block given, returns the computed matchdata:
'foo'.match('f') # => #<MatchData "f"> 'foo'.match('o') # => #<MatchData "o"> 'foo'.match('x') # => nil
If Integer argument offset is given, the search begins at index offset:
'foo'.match('f', 1) # => nil 'foo'.match('o', 1) # => #<MatchData "o">
With a block given, calls the block with the computed matchdata and returns the block’s return value:
'foo'.match(/o/) {|matchdata| matchdata } # => #<MatchData "o"> 'foo'.match(/x/) {|matchdata| matchdata } # => nil 'foo'.match(/f/, 1) {|matchdata| matchdata } # => nil
Returns true or false based on whether a match is found for self and pattern.
Note: does not update Global Variables at Regexp.
Computes regexp by converting pattern (if not already a Regexp).
regexp = Regexp.new(pattern)
Returns true if self+.match(regexp) returns a MatchData object, false otherwise:
'foo'.match?(/o/) # => true 'foo'.match?('o') # => true 'foo'.match?(/x/) # => false
If Integer argument offset is given, the search begins at index offset:
'foo'.match?('f', 1) # => false 'foo'.match?('o', 1) # => true
Concatenates each object in objects to self and returns self:
s = 'foo' s.concat('bar', 'baz') # => "foobarbaz" s # => "foobarbaz"
For each given object object that is an Integer, the value is considered a codepoint and converted to a character before concatenation:
s = 'foo' s.concat(32, 'bar', 32, 'baz') # => "foo bar baz"
Related: String#<<, which takes a single argument.
Returns a 3-element array of substrings of self.
Matches a pattern against self, scanning from the beginning. The pattern is:
string_or_regexp itself, if it is a Regexp.
Regexp.quote(string_or_regexp), if string_or_regexp is a string.
If the pattern is matched, returns pre-match, first-match, post-match:
'hello'.partition('l') # => ["he", "l", "lo"] 'hello'.partition('ll') # => ["he", "ll", "o"] 'hello'.partition('h') # => ["", "h", "ello"] 'hello'.partition('o') # => ["hell", "o", ""] 'hello'.partition(/l+/) #=> ["he", "ll", "o"] 'hello'.partition('') # => ["", "", "hello"] 'тест'.partition('т') # => ["", "т", "ест"] 'こんにちは'.partition('に') # => ["こん", "に", "ちは"]
If the pattern is not matched, returns a copy of self and two empty strings:
'hello'.partition('x') # => ["hello", "", ""]
Related: String#rpartition, String#split.