Calls the block, if given with each element of self; removes from self those elements for which the block returns false or nil.
Returns self if any elements were removed:
a = [:foo, 'bar', 2, :bam] a.select! {|element| element.to_s.start_with?('b') } # => ["bar", :bam]
Returns nil if no elements were removed.
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2, :bam] a.select! # => #<Enumerator: [:foo, "bar", 2, :bam]:select!>
Array#filter! is an alias for Array#select!.
Calls the block, if given, with each element of self; returns a new Array containing those elements of self for which the block returns a truthy value:
a = [:foo, 'bar', 2, :bam] a1 = a.select {|element| element.to_s.start_with?('b') } a1 # => ["bar", :bam]
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2, :bam] a.select # => #<Enumerator: [:foo, "bar", 2, :bam]:select>
Array#filter is an alias for Array#select.
Calls the block, if given with each element of self; removes from self those elements for which the block returns false or nil.
Returns self if any elements were removed:
a = [:foo, 'bar', 2, :bam] a.select! {|element| element.to_s.start_with?('b') } # => ["bar", :bam]
Returns nil if no elements were removed.
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2, :bam] a.select! # => #<Enumerator: [:foo, "bar", 2, :bam]:select!>
Array#filter! is an alias for Array#select!.
Removes zero or more elements from self.
When no block is given, removes from self each element ele such that ele == obj; returns the last deleted element:
s1 = 'bar'; s2 = 'bar' a = [:foo, s1, 2, s2] a.delete('bar') # => "bar" a # => [:foo, 2]
Returns nil if no elements removed.
When a block is given, removes from self each element ele such that ele == obj.
If any such elements are found, ignores the block and returns the last deleted element:
s1 = 'bar'; s2 = 'bar' a = [:foo, s1, 2, s2] deleted_obj = a.delete('bar') {|obj| fail 'Cannot happen' } a # => [:foo, 2]
If no such elements are found, returns the block’s return value:
a = [:foo, 'bar', 2] a.delete(:nosuch) {|obj| "#{obj} not found" } # => "nosuch not found"
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]
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2] a.reject # => #<Enumerator: [:foo, "bar", 2]:reject>
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.
Returns a new Enumerator if no block given:
a = [:foo, 'bar', 2] a.reject! # => #<Enumerator: [:foo, "bar", 2]:reject!>
When no block given, returns a new Array new_array of size self.size whose elements are Arrays.
Each nested array new_array[n] is of size other_arrays.size+1, and contains:
The nth element of self.
The nth element of each of the other_arrays.
If all other_arrays and self are the same size:
a = [:a0, :a1, :a2, :a3] b = [:b0, :b1, :b2, :b3] c = [:c0, :c1, :c2, :c3] d = a.zip(b, c) d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]
If any array in other_arrays is smaller than self, fills to self.size with nil:
a = [:a0, :a1, :a2, :a3] b = [:b0, :b1, :b2] c = [:c0, :c1] d = a.zip(b, c) d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, nil], [:a3, nil, nil]]
If any array in other_arrays is larger than self, its trailing elements are ignored:
a = [:a0, :a1, :a2, :a3] b = [:b0, :b1, :b2, :b3, :b4] c = [:c0, :c1, :c2, :c3, :c4, :c5] d = a.zip(b, c) d # => [[:a0, :b0, :c0], [:a1, :b1, :c1], [:a2, :b2, :c2], [:a3, :b3, :c3]]
When a block is given, calls the block with each of the sub-arrays (formed as above); returns nil:
a = [:a0, :a1, :a2, :a3] b = [:b0, :b1, :b2, :b3] c = [:c0, :c1, :c2, :c3] a.zip(b, c) {|sub_array| p sub_array} # => nil
Output:
[:a0, :b0, :c0] [:a1, :b1, :c1] [:a2, :b2, :c2] [:a3, :b3, :c3]
Replaces the content of self with the content of other_array; returns self:
a = [:foo, 'bar', 2] a.replace(['foo', :bar, 3]) # => ["foo", :bar, 3]
Replaces specified elements in self with specified objects; returns self.
With argument obj and no block given, replaces all elements with that one object:
a = ['a', 'b', 'c', 'd'] a # => ["a", "b", "c", "d"] a.fill(:X) # => [:X, :X, :X, :X]
With arguments obj and Integer start, and no block given, replaces elements based on the given start.
If start is in range (0 <= start < array.size), replaces all elements from offset start through the end:
a = ['a', 'b', 'c', 'd'] a.fill(:X, 2) # => ["a", "b", :X, :X]
If start is too large (start >= array.size), does nothing:
a = ['a', 'b', 'c', 'd'] a.fill(:X, 4) # => ["a", "b", "c", "d"] a = ['a', 'b', 'c', 'd'] a.fill(:X, 5) # => ["a", "b", "c", "d"]
If start is negative, counts from the end (starting index is start + array.size):
a = ['a', 'b', 'c', 'd'] a.fill(:X, -2) # => ["a", "b", :X, :X]
If start is too small (less than and far from zero), replaces all elements:
a = ['a', 'b', 'c', 'd'] a.fill(:X, -6) # => [:X, :X, :X, :X] a = ['a', 'b', 'c', 'd'] a.fill(:X, -50) # => [:X, :X, :X, :X]
With arguments obj, Integer start, and Integer length, and no block given, replaces elements based on the given start and length.
If start is in range, replaces length elements beginning at offset start:
a = ['a', 'b', 'c', 'd'] a.fill(:X, 1, 1) # => ["a", :X, "c", "d"]
If start is negative, counts from the end:
a = ['a', 'b', 'c', 'd'] a.fill(:X, -2, 1) # => ["a", "b", :X, "d"]
If start is large (start >= array.size), extends self with nil:
a = ['a', 'b', 'c', 'd'] a.fill(:X, 5, 0) # => ["a", "b", "c", "d", nil] a = ['a', 'b', 'c', 'd'] a.fill(:X, 5, 2) # => ["a", "b", "c", "d", nil, :X, :X]
If length is zero or negative, replaces no elements:
a = ['a', 'b', 'c', 'd'] a.fill(:X, 1, 0) # => ["a", "b", "c", "d"] a.fill(:X, 1, -1) # => ["a", "b", "c", "d"]
With arguments obj and Range range, and no block given, replaces elements based on the given range.
If the range is positive and ascending (0 < range.begin <= range.end), replaces elements from range.begin to range.end:
a = ['a', 'b', 'c', 'd'] a.fill(:X, (1..1)) # => ["a", :X, "c", "d"]
If range.first is negative, replaces no elements:
a = ['a', 'b', 'c', 'd'] a.fill(:X, (-1..1)) # => ["a", "b", "c", "d"]
If range.last is negative, counts from the end:
a = ['a', 'b', 'c', 'd'] a.fill(:X, (0..-2)) # => [:X, :X, :X, "d"] a = ['a', 'b', 'c', 'd'] a.fill(:X, (1..-2)) # => ["a", :X, :X, "d"]
If range.last and range.last are both negative, both count from the end of the array:
a = ['a', 'b', 'c', 'd'] a.fill(:X, (-1..-1)) # => ["a", "b", "c", :X] a = ['a', 'b', 'c', 'd'] a.fill(:X, (-2..-2)) # => ["a", "b", :X, "d"]
With no arguments and a block given, calls the block with each index; replaces the corresponding element with the block’s return value:
a = ['a', 'b', 'c', 'd'] a.fill { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"]
With argument start and a block given, calls the block with each index from offset start to the end; replaces the corresponding element with the block’s return value.
If start is in range (0 <= start < array.size), replaces from offset start to the end:
a = ['a', 'b', 'c', 'd'] a.fill(1) { |index| "new_#{index}" } # => ["a", "new_1", "new_2", "new_3"]
If start is too large(start >= array.size), does nothing:
a = ['a', 'b', 'c', 'd'] a.fill(4) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"] a = ['a', 'b', 'c', 'd'] a.fill(4) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
If start is negative, counts from the end:
a = ['a', 'b', 'c', 'd'] a.fill(-2) { |index| "new_#{index}" } # => ["a", "b", "new_2", "new_3"]
If start is too small (start <= -array.size, replaces all elements:
a = ['a', 'b', 'c', 'd'] a.fill(-6) { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"] a = ['a', 'b', 'c', 'd'] a.fill(-50) { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "new_3"]
With arguments start and length, and a block given, calls the block for each index specified by start length; replaces the corresponding element with the block’s return value.
If start is in range, replaces length elements beginning at offset start:
a = ['a', 'b', 'c', 'd'] a.fill(1, 1) { |index| "new_#{index}" } # => ["a", "new_1", "c", "d"]
If start is negative, counts from the end:
a = ['a', 'b', 'c', 'd'] a.fill(-2, 1) { |index| "new_#{index}" } # => ["a", "b", "new_2", "d"]
If start is large (start >= array.size), extends self with nil:
a = ['a', 'b', 'c', 'd'] a.fill(5, 0) { |index| "new_#{index}" } # => ["a", "b", "c", "d", nil] a = ['a', 'b', 'c', 'd'] a.fill(5, 2) { |index| "new_#{index}" } # => ["a", "b", "c", "d", nil, "new_5", "new_6"]
If length is zero or less, replaces no elements:
a = ['a', 'b', 'c', 'd'] a.fill(1, 0) { |index| "new_#{index}" } # => ["a", "b", "c", "d"] a.fill(1, -1) { |index| "new_#{index}" } # => ["a", "b", "c", "d"]
With arguments obj and range, and a block given, calls the block with each index in the given range; replaces the corresponding element with the block’s return value.
If the range is positive and ascending (range 0 < range.begin <= range.end, replaces elements from range.begin to range.end:
a = ['a', 'b', 'c', 'd'] a.fill(1..1) { |index| "new_#{index}" } # => ["a", "new_1", "c", "d"]
If range.first is negative, does nothing:
a = ['a', 'b', 'c', 'd'] a.fill(-1..1) { |index| fail 'Cannot happen' } # => ["a", "b", "c", "d"]
If range.last is negative, counts from the end:
a = ['a', 'b', 'c', 'd'] a.fill(0..-2) { |index| "new_#{index}" } # => ["new_0", "new_1", "new_2", "d"] a = ['a', 'b', 'c', 'd'] a.fill(1..-2) { |index| "new_#{index}" } # => ["a", "new_1", "new_2", "d"]
If range.first and range.last are both negative, both count from the end:
a = ['a', 'b', 'c', 'd'] a.fill(-1..-1) { |index| "new_#{index}" } # => ["a", "b", "c", "new_3"] a = ['a', 'b', 'c', 'd'] a.fill(-2..-2) { |index| "new_#{index}" } # => ["a", "b", "new_2", "d"]
Returns true if for some index i in self, obj == self[i]; otherwise false:
[0, 1, 2].include?(2) # => true [0, 1, 2].include?(3) # => false
Returns -1, 0, or 1 as self is less than, equal to, or greater than other_array. For each index i in self, evaluates result = self[i] <=> other_array[i].
Returns -1 if any result is -1:
[0, 1, 2] <=> [0, 1, 3] # => -1
Returns 1 if any result is 1:
[0, 1, 2] <=> [0, 1, 1] # => 1
When all results are zero:
Returns -1 if array is smaller than other_array:
[0, 1, 2] <=> [0, 1, 2, 3] # => -1
Returns 1 if array is larger than other_array:
[0, 1, 2] <=> [0, 1] # => 1
Returns 0 if array and other_array are the same size:
[0, 1, 2] <=> [0, 1, 2] # => 0
Returns elements from self; does not modify self.
When a single Integer argument index is given, returns the element at offset index:
a = [:foo, 'bar', 2] a[0] # => :foo a[2] # => 2 a # => [:foo, "bar", 2]
If index is negative, counts relative to the end of self:
a = [:foo, 'bar', 2] a[-1] # => 2 a[-2] # => "bar"
If index is out of range, returns nil.
When two Integer arguments start and length are given, returns a new Array of size length containing successive elements beginning at offset start:
a = [:foo, 'bar', 2] a[0, 2] # => [:foo, "bar"] a[1, 2] # => ["bar", 2]
If start + length is greater than self.length, returns all elements from offset start to the end:
a = [:foo, 'bar', 2] a[0, 4] # => [:foo, "bar", 2] a[1, 3] # => ["bar", 2] a[2, 2] # => [2]
If start == self.size and length >= 0, returns a new empty Array.
If length is negative, returns nil.
When a single Range argument range is given, treats range.min as start above and range.size as length above:
a = [:foo, 'bar', 2] a[0..1] # => [:foo, "bar"] a[1..2] # => ["bar", 2]
Special case: If range.start == a.size, returns a new empty Array.
If range.end is negative, calculates the end index from the end:
a = [:foo, 'bar', 2] a[0..-1] # => [:foo, "bar", 2] a[0..-2] # => [:foo, "bar"] a[0..-3] # => [:foo]
If range.start is negative, calculates the start index from the end:
a = [:foo, 'bar', 2] a[-1..2] # => [2] a[-2..2] # => ["bar", 2] a[-3..2] # => [:foo, "bar", 2]
If range.start is larger than the array size, returns nil.
a = [:foo, 'bar', 2] a[4..1] # => nil a[4..0] # => nil a[4..-1] # => nil
When a single Enumerator::ArithmeticSequence argument aseq is given, returns an Array of elements corresponding to the indexes produced by the sequence.
a = ['--', 'data1', '--', 'data2', '--', 'data3'] a[(1..).step(2)] # => ["data1", "data2", "data3"]
Unlike slicing with range, if the start or the end of the arithmetic sequence is larger than array size, throws RangeError.
a = ['--', 'data1', '--', 'data2', '--', 'data3'] a[(1..11).step(2)] # RangeError (((1..11).step(2)) out of range) a[(7..).step(2)] # RangeError (((7..).step(2)) out of range)
If given a single argument, and its type is not one of the listed, tries to convert it to Integer, and raises if it is impossible:
a = [:foo, 'bar', 2] # Raises TypeError (no implicit conversion of Symbol into Integer): a[:foo]
Array#slice is an alias for Array#[].
Removes and returns elements from self.
When the only argument is an Integer n, removes and returns the nth element in self:
a = [:foo, 'bar', 2] a.slice!(1) # => "bar" a # => [:foo, 2]
If n is negative, counts backwards from the end of self:
a = [:foo, 'bar', 2] a.slice!(-1) # => 2 a # => [:foo, "bar"]
If n is out of range, returns nil.
When the only arguments are Integers start and length, removes length elements from self beginning at offset start; returns the deleted objects in a new Array:
a = [:foo, 'bar', 2] a.slice!(0, 2) # => [:foo, "bar"] a # => [2]
If start + length exceeds the array size, removes and returns all elements from offset start to the end:
a = [:foo, 'bar', 2] a.slice!(1, 50) # => ["bar", 2] a # => [:foo]
If start == a.size and length is non-negative, returns a new empty Array.
If length is negative, returns nil.
When the only argument is a Range object range, treats range.min as start above and range.size as length above:
a = [:foo, 'bar', 2] a.slice!(1..2) # => ["bar", 2] a # => [:foo]
If range.start == a.size, returns a new empty Array.
If range.start is larger than the array size, returns nil.
If range.end is negative, counts backwards from the end of the array:
a = [:foo, 'bar', 2] a.slice!(0..-2) # => [:foo, "bar"] a # => [2]
If range.start is negative, calculates the start index backwards from the end of the array:
a = [:foo, 'bar', 2] a.slice!(-2..2) # => ["bar", 2] a # => [:foo]
Returns the first element in self that is an Array whose first element == obj:
a = [{foo: 0}, [2, 4], [4, 5, 6], [4, 5]] a.assoc(4) # => [4, 5, 6]
Returns nil if no such element is found.
Related: rassoc.
Returns a new Array containing all elements of array followed by all elements of other_array:
a = [0, 1] + [2, 3] a # => [0, 1, 2, 3]
Related: concat.
When non-negative argument Integer n is given, returns a new Array built by concatenating the n copies of self:
a = ['x', 'y'] a * 3 # => ["x", "y", "x", "y", "x", "y"]
When String argument string_separator is given, equivalent to array.join(string_separator):
[0, [0, 1], {foo: 0}] * ', ' # => "0, 0, 1, {:foo=>0}"
Returns a new Array containing only those elements from array that are not found in Array other_array; items are compared using eql?; the order from array is preserved:
[0, 1, 1, 2, 1, 1, 3, 1, 1] - [1] # => [0, 2, 3] [0, 1, 2, 3] - [3, 0] # => [1, 2] [0, 1, 2] - [4] # => [0, 1, 2]
Related: Array#difference.
Returns a new Array containing each element found in both array and Array other_array; duplicates are omitted; items are compared using eql?:
[0, 1, 2, 3] & [1, 2] # => [1, 2] [0, 1, 0, 1] & [0, 1] # => [0, 1]
Preserves order from array:
[0, 1, 2] & [3, 2, 1, 0] # => [0, 1, 2]
Related: Array#intersection.
Returns the union of array and Array other_array; duplicates are removed; order is preserved; items are compared using eql?:
[0, 1] | [2, 3] # => [0, 1, 2, 3] [0, 1, 1] | [2, 2, 3] # => [0, 1, 2, 3] [0, 1, 2] | [3, 2, 1, 0] # => [0, 1, 2, 3]
Related: Array#union.
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 one of the following:
The minimum-valued element from self.
A new Array of minimum-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 minimum value per method <=>:
[0, 1, 2].min # => 0
With Integer argument n and no block, returns a new Array with at most n elements, in ascending order per method <=>:
[0, 1, 2, 3].min(3) # => [0, 1, 2] [0, 1, 2, 3].min(6) # => [0, 1, 2, 3]
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 minimum value per the block:
['0', '00', '000'].min { |a, b| a.size <=> b.size } # => "0"
With an argument n and a block, returns a new Array with at most n elements, in ascending order per the block:
['0', '00', '000'].min(2) {|a, b| a.size <=> b.size } # => ["0", "00"]
Returns a new 2-element Array containing the minimum and maximum values from self, either per method <=> or per a given block:.
When no block is given, each element in self must respond to method <=> with an Integer; returns a new 2-element Array containing the minimum and maximum values from self, per method <=>:
[0, 1, 2].minmax # => [0, 2]
When a block is given, the block must return an Integer; the block is called self.size-1 times to compare elements; returns a new 2-element Array containing the minimum and maximum values from self, per the block:
['0', '00', '000'].minmax {|a, b| a.size <=> b.size } # => ["0", "000"]
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 duplicates using method eql? to compare:
a = [0, 0, 1, 1, 2, 2] a.uniq # => [0, 1, 2]
With a block given, calls the block for each element; identifies (using method eql?) and omits duplicate values, that is, those elements for which the block returns the same value:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb'] a.uniq {|element| element.size } # => ["a", "aa", "aaa"]
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.
Returns self if any elements removed:
a = [0, 0, 1, 1, 2, 2] a.uniq! # => [0, 1, 2]
Returns nil if no elements removed.
With a block given, calls the block for each element; identifies (using method eql?) and removes elements for which the block returns duplicate values.
Returns self if any elements removed:
a = ['a', 'aa', 'aaa', 'b', 'bb', 'bbb'] a.uniq! {|element| element.size } # => ['a', 'aa', 'aaa']
Returns nil if no elements removed.
Returns a new Array containing all non-nil elements from self:
a = [nil, 0, nil, 1, nil, 2, nil] a.compact # => [0, 1, 2]