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].
Returns self.
Raises an exception if the value for freeze is neither true nor nil.
Related: Numeric#dup.
Returns self if self is not a zero value, nil otherwise; uses method zero? for the evaluation.
The returned self allows the method to be chained:
a = %w[z Bb bB bb BB a aA Aa AA A] a.sort {|a, b| (a.downcase <=> b.downcase).nonzero? || a <=> b } # => ["A", "a", "AA", "Aa", "aA", "BB", "Bb", "bB", "bb", "z"]
Of the Core and Standard Library classes, Integer, Float, Rational, and Complex use this implementation.
Related: zero?
Returns self rounded to the nearest value with a precision of digits decimal digits.
Numeric implements this by converting self to a Float and invoking Float#round.
Returns true if self is greater than 0, false otherwise.
Returns true if self is less than 0, false otherwise.
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 a printable version of self, enclosed in double-quotes, and with special characters escaped:
s = "foo\tbar\tbaz\n" s.inspect # => "\"foo\\tbar\\tbaz\\n\""
Returns a string containing the downcased characters in self:
s = 'Hello World!' # => "Hello World!" s.downcase # => "hello world!"
The casing may be affected by the given options; see Case Mapping.
Related: String#downcase!, String#upcase, String#upcase!.