Returns the new string formed by calling method #inspect on each array element:
a = [:foo, 'bar', 2] a.inspect # => "[:foo, \"bar\", 2]"
Related: see Methods for Converting.
Returns a new array containing only those elements from self that are not found in any of the given 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] [0, 1, 2].difference # => [0, 1, 2]
Returns a copy of self if no arguments are given.
Related: Array#-; see also Methods for Combining.
Returns whether other_array has at least one element that is #eql? to some element of self:
[1, 2, 3].intersect?([3, 4, 5]) # => true [1, 2, 3].intersect?([4, 5, 6]) # => false
Each element must correctly implement method #hash.
Related: see Methods for Querying.
Prepends the given objects to self:
a = [:foo, 'bar', 2] a.unshift(:bam, :bat) # => [:bam, :bat, :foo, "bar", 2]
Related: Array#shift; see also Methods for Assigning.
With a block given, returns a new array whose elements are all those from self for which the block returns false or nil:
a = [:foo, 'bar', 2, 'bat'] a1 = a.reject {|element| element.to_s.start_with?('b') } a1 # => [:foo, 2]
With no block given, returns a new Enumerator.
Related: Methods for Fetching.
With a block given, calls the block with each element of self; removes each element for which the block returns a truthy value.
Returns self if any elements removed:
a = [:foo, 'bar', 2, 'bat'] a.reject! {|element| element.to_s.start_with?('b') } # => [:foo, 2]
Returns nil if no elements removed.
With no block given, returns a new Enumerator.
Related: see Methods for Deleting.
Returns whether for some element element in self, object == element:
[0, 1, 2].include?(2) # => true [0, 1, 2].include?(2.0) # => true [0, 1, 2].include?(2.1) # => false
Related: see Methods for Querying.
Returns a new array containing those elements from self that are not duplicates, the first occurrence always being retained.
With no block given, identifies and omits duplicate elements using method eql? to compare elements:
a = [0, 0, 1, 1, 2, 2] a.uniq # => [0, 1, 2]
With a block given, calls the block for each element; identifies and omits “duplicate” elements using method eql? to compare block return values; that is, an element is a duplicate if its block return value is the same as that of a previous element:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb'] a.uniq {|element| element.size } # => ["a", "aa", "aaa"]
Related: Methods for Fetching.
Removes duplicate elements from self, the first occurrence always being retained; returns self if any elements removed, nil otherwise.
With no block given, identifies and removes elements using method eql? to compare elements:
a = [0, 0, 1, 1, 2, 2] a.uniq! # => [0, 1, 2] a.uniq! # => nil
With a block given, calls the block for each element; identifies and omits “duplicate” elements using method eql? to compare block return values; that is, an element is a duplicate if its block return value is the same as that of a previous element:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb'] a.uniq! {|element| element.size } # => ["a", "aa", "aaa"] a.uniq! {|element| element.size } # => nil
Related: see Methods for Deleting.
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 count of specified elements.
With no argument and no block, returns the count of all elements:
[0, :one, 'two', 3, 3.0].count # => 5
With argument object given, returns the count of elements == to object:
[0, :one, 'two', 3, 3.0].count(3) # => 2
With no argument and a block given, calls the block with each element; returns the count of elements for which the block returns a truthy value:
[0, 1, 2, 3].count {|element| element > 1 } # => 2
With argument object and a block given, issues a warning, ignores the block, and returns the count of elements == to object.
Related: see Methods for Querying.
Returns true if no element of self meets a given criterion, false otherwise.
With no block given and no argument, returns true if self has no truthy elements, false otherwise:
[nil, false].none? # => true [nil, 0, false].none? # => false [].none? # => true
With argument object given, returns false if for any element element, object === element; true otherwise:
['food', 'drink'].none?(/bar/) # => true ['food', 'drink'].none?(/foo/) # => false [].none?(/foo/) # => true [0, 1, 2].none?(3) # => true [0, 1, 2].none?(1) # => false
With a block given, calls the block with each element in self; returns true if the block returns no truthy value, false otherwise:
[0, 1, 2].none? {|element| element > 3 } # => true [0, 1, 2].none? {|element| element > 1 } # => false
Related: see Methods for Querying.
Returns true if exactly one element of self meets a given criterion.
With no block given and no argument, returns true if self has exactly one truthy element, false otherwise:
[nil, 0].one? # => true [0, 0].one? # => false [nil, nil].one? # => false [].one? # => false
With a block given, calls the block with each element in self; returns true if the block a truthy value for exactly one element, false otherwise:
[0, 1, 2].one? {|element| element > 0 } # => false [0, 1, 2].one? {|element| element > 1 } # => true [0, 1, 2].one? {|element| element > 2 } # => false
With argument object given, returns true if for exactly one element element, object === element; false otherwise:
[0, 1, 2].one?(0) # => true [0, 0, 1].one?(0) # => false [1, 1, 2].one?(0) # => false ['food', 'drink'].one?(/bar/) # => false ['food', 'drink'].one?(/foo/) # => true [].one?(/foo/) # => false
Related: see Methods for Querying.
Returns self rounded to the nearest value with a precision of ndigits decimal digits.
When ndigits is negative, the returned value has at least ndigits.abs trailing zeros:
555.round(-1) # => 560 555.round(-2) # => 600 555.round(-3) # => 1000 -555.round(-2) # => -600 555.round(-4) # => 0
Returns self when ndigits is zero or positive.
555.round # => 555 555.round(1) # => 555 555.round(50) # => 555
If keyword argument half is given, and self is equidistant from the two candidate values, the rounding is according to the given half value:
:up or nil: round away from zero:
25.round(-1, half: :up) # => 30 (-25).round(-1, half: :up) # => -30
:down: round toward zero:
25.round(-1, half: :down) # => 20 (-25).round(-1, half: :down) # => -20
:even: round toward the candidate whose last nonzero digit is even:
25.round(-1, half: :even) # => 20 15.round(-1, half: :even) # => 20 (-25).round(-1, half: :even) # => -20
Raises and exception if the value for half is invalid.
Related: Integer#truncate.
Returns a string containing the place-value representation of self in radix base (in 2..36).
12345.to_s # => "12345" 12345.to_s(2) # => "11000000111001" 12345.to_s(8) # => "30071" 12345.to_s(10) # => "12345" 12345.to_s(16) # => "3039" 12345.to_s(36) # => "9ix" 78546939656932.to_s(36) # => "rubyrules"
Raises an exception if base is out of range.
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 a new Complex object formed from the arguments, each of which must be an instance of Numeric, or an instance of one of its subclasses: Complex, Float, Integer, Rational; see Rectangular Coordinates:
Complex.rect(3) # => (3+0i) Complex.rect(3, Math::PI) # => (3+3.141592653589793i) Complex.rect(-3, -Math::PI) # => (-3-3.141592653589793i)
Complex.rectangular is an alias for Complex.rect.
Returns a new Complex object formed from the arguments, each of which must be an instance of Numeric, or an instance of one of its subclasses: Complex, Float, Integer, Rational; see Rectangular Coordinates:
Complex.rect(3) # => (3+0i) Complex.rect(3, Math::PI) # => (3+3.141592653589793i) Complex.rect(-3, -Math::PI) # => (-3-3.141592653589793i)
Complex.rectangular is an alias for Complex.rect.
Returns the conjugate of self, Complex.rect(self.imag, self.real):
Complex.rect(1, 2).conj # => (1-2i)
Returns the conjugate of self, Complex.rect(self.imag, self.real):
Complex.rect(1, 2).conj # => (1-2i)
Returns a string representation of self:
Complex.rect(2).inspect # => "(2+0i)" Complex.rect(-8, 6).inspect # => "(-8+6i)" Complex.rect(0, Rational(1, 2)).inspect # => "(0+(1/2)*i)" Complex.rect(0, Float::INFINITY).inspect # => "(0+Infinity*i)" Complex.rect(Float::NAN, Float::NAN).inspect # => "(NaN+NaN*i)"
Returns array [self, 0].