Returns the element at Integer offset index; does not modify self.
a = [:foo, 'bar', 2] a.at(0) # => :foo a.at(2) # => 2
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]
Iterates over array elements.
When a block given, passes each successive array element to the block; returns self:
a = [:foo, 'bar', 2] a.each {|element| puts "#{element.class} #{element}" }
Output:
Symbol foo String bar Integer 2
Allows the array to be modified during iteration:
a = [:foo, 'bar', 2] a.each {|element| puts element; a.clear if element.to_s.start_with?('b') }
Output:
foo bar
When no block given, returns a new Enumerator:
a = [:foo, 'bar', 2] e = a.each e # => #<Enumerator: [:foo, "bar", 2]:each> a1 = e.each {|element| puts "#{element.class} #{element}" }
Output:
Symbol foo String bar Integer 2
Related: each_index, reverse_each.
Returns a new Array formed from self with elements rotated from one end to the other.
When no argument given, returns a new Array that is like self, except that the first element has been rotated to the last position:
a = [:foo, 'bar', 2, 'bar'] a1 = a.rotate a1 # => ["bar", 2, "bar", :foo]
When given a non-negative Integer count, returns a new Array with count elements rotated from the beginning to the end:
a = [:foo, 'bar', 2] a1 = a.rotate(2) a1 # => [2, :foo, "bar"]
If count is large, uses count % array.size as the count:
a = [:foo, 'bar', 2] a1 = a.rotate(20) a1 # => [2, :foo, "bar"]
If count is zero, returns a copy of self, unmodified:
a = [:foo, 'bar', 2] a1 = a.rotate(0) a1 # => [:foo, "bar", 2]
When given a negative Integer count, rotates in the opposite direction, from end to beginning:
a = [:foo, 'bar', 2] a1 = a.rotate(-2) a1 # => ["bar", 2, :foo]
If count is small (far from zero), uses count % array.size as the count:
a = [:foo, 'bar', 2] a1 = a.rotate(-5) a1 # => ["bar", 2, :foo]
Rotates self in place by moving elements from one end to the other; returns self.
When no argument given, rotates the first element to the last position:
a = [:foo, 'bar', 2, 'bar'] a.rotate! # => ["bar", 2, "bar", :foo]
When given a non-negative Integer count, rotates count elements from the beginning to the end:
a = [:foo, 'bar', 2] a.rotate!(2) a # => [2, :foo, "bar"]
If count is large, uses count % array.size as the count:
a = [:foo, 'bar', 2] a.rotate!(20) a # => [2, :foo, "bar"]
If count is zero, returns self unmodified:
a = [:foo, 'bar', 2] a.rotate!(0) a # => [:foo, "bar", 2]
When given a negative Integer count, rotates in the opposite direction, from end to beginning:
a = [:foo, 'bar', 2] a.rotate!(-2) a # => ["bar", 2, :foo]
If count is small (far from zero), uses count % array.size as the count:
a = [:foo, 'bar', 2] a.rotate!(-5) a # => ["bar", 2, :foo]
Calls the block, if given, with each element of self; returns a new Array whose elements are the return values from the block:
a = [:foo, 'bar', 2] a1 = a.map {|element| element.class } a1 # => [Symbol, String, Integer]
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2] a1 = a.map a1 # => #<Enumerator: [:foo, "bar", 2]:map>
Array#collect is an alias for Array#map.
Calls the block, if given, with each element; replaces the element with the block’s return value:
a = [:foo, 'bar', 2] a.map! { |element| element.class } # => [Symbol, String, Integer]
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2] a1 = a.map! a1 # => #<Enumerator: [:foo, "bar", 2]:map!>
Array#collect! is an alias for Array#map!.
Returns one of the following:
The maximum-valued element from self.
A new Array of maximum-valued elements selected from self.
When no block is given, each element in self must respond to method <=> with an Integer.
With no argument and no block, returns the element in self having the maximum value per method <=>:
[0, 1, 2].max # => 2
With an argument Integer n and no block, returns a new Array with at most n elements, in descending order per method <=>:
[0, 1, 2, 3].max(3) # => [3, 2, 1] [0, 1, 2, 3].max(6) # => [3, 2, 1, 0]
When a block is given, the block must return an Integer.
With a block and no argument, calls the block self.size-1 times to compare elements; returns the element having the maximum value per the block:
['0', '00', '000'].max {|a, b| a.size <=> b.size } # => "000"
With an argument n and a block, returns a new Array with at most n elements, in descending order per the block:
['0', '00', '000'].max(2) {|a, b| a.size <=> b.size } # => ["000", "00"]
Returns a new Array that is a recursive flattening of self:
Each non-Array element is unchanged.
Each Array is replaced by its individual elements.
With non-negative Integer argument level, flattens recursively through level levels:
a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten(0) # => [0, [1, [2, 3], 4], 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten(1) # => [0, 1, [2, 3], 4, 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten(2) # => [0, 1, 2, 3, 4, 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten(3) # => [0, 1, 2, 3, 4, 5]
With no argument, a nil argument, or with negative argument level, flattens all levels:
a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten # => [0, 1, 2, 3, 4, 5] [0, 1, 2].flatten # => [0, 1, 2] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten(-1) # => [0, 1, 2, 3, 4, 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten(-2) # => [0, 1, 2, 3, 4, 5] [0, 1, 2].flatten(-1) # => [0, 1, 2]
Replaces each nested Array in self with the elements from that Array; returns self if any changes, nil otherwise.
With non-negative Integer argument level, flattens recursively through level levels:
a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten!(1) # => [0, 1, [2, 3], 4, 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten!(2) # => [0, 1, 2, 3, 4, 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten!(3) # => [0, 1, 2, 3, 4, 5] [0, 1, 2].flatten!(1) # => nil
With no argument, a nil argument, or with negative argument level, flattens all levels:
a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten! # => [0, 1, 2, 3, 4, 5] [0, 1, 2].flatten! # => nil a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten!(-1) # => [0, 1, 2, 3, 4, 5] a = [ 0, [ 1, [2, 3], 4 ], 5 ] a.flatten!(-2) # => [0, 1, 2, 3, 4, 5] [0, 1, 2].flatten!(-1) # => nil
When invoked with a block, yield all permutations of elements of self; returns self. The order of permutations is indeterminate.
When a block and an in-range positive Integer argument n (0 < n <= self.size) are given, calls the block with all n-tuple permutations of self.
Example:
a = [0, 1, 2] a.permutation(2) {|permutation| p permutation }
Output:
[0, 1] [0, 2] [1, 0] [1, 2] [2, 0] [2, 1]
Another example:
a = [0, 1, 2] a.permutation(3) {|permutation| p permutation }
Output:
[0, 1, 2] [0, 2, 1] [1, 0, 2] [1, 2, 0] [2, 0, 1] [2, 1, 0]
When n is zero, calls the block once with a new empty Array:
a = [0, 1, 2] a.permutation(0) {|permutation| p permutation }
Output:
[]
When n is out of range (negative or larger than self.size), does not call the block:
a = [0, 1, 2] a.permutation(-1) {|permutation| fail 'Cannot happen' } a.permutation(4) {|permutation| fail 'Cannot happen' }
When a block given but no argument, behaves the same as a.permutation(a.size):
a = [0, 1, 2] a.permutation {|permutation| p permutation }
Output:
[0, 1, 2] [0, 2, 1] [1, 0, 2] [1, 2, 0] [2, 0, 1] [2, 1, 0]
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.permutation # => #<Enumerator: [0, 1, 2]:permutation> a.permutation(2) # => #<Enumerator: [0, 1, 2]:permutation(2)>
Calls the block, if given, with combinations of elements of self; returns self. The order of combinations is indeterminate.
When a block and an in-range positive Integer argument n (0 < n <= self.size) are given, calls the block with all n-tuple combinations of self.
Example:
a = [0, 1, 2] a.combination(2) {|combination| p combination }
Output:
[0, 1] [0, 2] [1, 2]
Another example:
a = [0, 1, 2] a.combination(3) {|combination| p combination }
Output:
[0, 1, 2]
When n is zero, calls the block once with a new empty Array:
a = [0, 1, 2] a1 = a.combination(0) {|combination| p combination }
Output:
[]
When n is out of range (negative or larger than self.size), does not call the block:
a = [0, 1, 2] a.combination(-1) {|combination| fail 'Cannot happen' } a.combination(4) {|combination| fail 'Cannot happen' }
Returns a new Enumerator if no block given:
a = [0, 1, 2] a.combination(2) # => #<Enumerator: [0, 1, 2]:combination(2)>
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 a 1-character string containing the character represented by the value of self, according to the given encoding.
65.chr # => "A" 0.chr # => "\x00" 255.chr # => "\xFF" string = 255.chr(Encoding::UTF_8) string.encoding # => Encoding::UTF_8
Raises an exception if self is negative.
Related: Integer#ord.
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.
Returns the remainder after dividing self by other.
Examples:
11.remainder(4) # => 3 11.remainder(-4) # => 3 -11.remainder(4) # => -3 -11.remainder(-4) # => -3 12.remainder(4) # => 0 12.remainder(-4) # => 0 -12.remainder(4) # => 0 -12.remainder(-4) # => 0 13.remainder(4.0) # => 1.0 13.remainder(Rational(4, 1)) # => (1/1)
Returns self.
Returns 1.
Returns the value as a rational. The optional argument eps is always ignored.
Returns the imaginary part.
Complex(7).imaginary #=> 0 Complex(9, -4).imaginary #=> -4
Returns the absolute part of its polar form.
Complex(-1).abs #=> 1 Complex(3.0, -4.0).abs #=> 5.0