When invoked with a block, yields all combinations of length n of elements from the array and then returns the array itself.
The implementation makes no guarantees about the order in which the combinations are yielded.
If no block is given, an Enumerator is returned instead.
Examples:
a = [1, 2, 3, 4] a.combination(1).to_a #=> [[1],[2],[3],[4]] a.combination(2).to_a #=> [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]] a.combination(3).to_a #=> [[1,2,3],[1,2,4],[1,3,4],[2,3,4]] a.combination(4).to_a #=> [[1,2,3,4]] a.combination(0).to_a #=> [[]] # one combination of length 0 a.combination(5).to_a #=> [] # no combinations of length 5
Returns an array of all combinations of elements from all arrays.
The length of the returned array is the product of the length of self and the argument arrays.
If given a block, product will yield all combinations and return self instead.
[1,2,3].product([4,5]) #=> [[1,4],[1,5],[2,4],[2,5],[3,4],[3,5]] [1,2].product([1,2]) #=> [[1,1],[1,2],[2,1],[2,2]] [1,2].product([3,4],[5,6]) #=> [[1,3,5],[1,3,6],[1,4,5],[1,4,6], # [2,3,5],[2,3,6],[2,4,5],[2,4,6]] [1,2].product() #=> [[1],[2]] [1,2].product([]) #=> []
Returns first n elements from the array.
If a negative number is given, raises an ArgumentError.
See also Array#drop
a = [1, 2, 3, 4, 5, 0] a.take(3) #=> [1, 2, 3]
Drops first n elements from ary and returns the rest of the elements in an array.
If a negative number is given, raises an ArgumentError.
See also Array#take
a = [1, 2, 3, 4, 5, 0] a.drop(3) #=> [4, 5, 0]
See also Enumerable#any?
Extracts the nested value specified by the sequence of idx objects by calling dig at each step, returning nil if any intermediate step is nil.
a = [[1, [2, 3]]] a.dig(0, 1, 1) #=> 3 a.dig(1, 2, 3) #=> nil a.dig(0, 0, 0) #=> NoMethodError, undefined method `dig' for 1:Fixnum [42, {foo: :bar}].dig(1, :foo) #=> :bar
Returns the number of elements in self. May be zero.
[ 1, 2, 3, 4, 5 ].length #=> 5 [].length #=> 0
Calculates the set of unambiguous abbreviations for the strings in self.
require 'abbrev' %w{ car cone }.abbrev #=> {"car"=>"car", "ca"=>"car", "cone"=>"cone", "con"=>"cone", "co"=>"cone"}
The optional pattern parameter is a pattern or a string. Only input strings that match the pattern or start with the string are included in the output hash.
%w{ fast boat day }.abbrev(/^.a/) #=> {"fast"=>"fast", "fas"=>"fast", "fa"=>"fast", "day"=>"day", "da"=>"day"} Abbrev.abbrev(%w{car box cone}, "ca") #=> {"car"=>"car", "ca"=>"car"}
See also Abbrev.abbrev
provides a unified clone operation, for REXML::XPathParser to use across multiple Object+ types
Builds a command line string from an argument list array joining all elements escaped for the Bourne shell and separated by a space.
See Shellwords.shelljoin for details.
Packs the contents of arr into a binary sequence according to the directives in aTemplateString (see the table below) Directives “A,” “a,” and “Z” may be followed by a count, which gives the width of the resulting field. The remaining directives also may take a count, indicating the number of array elements to convert. If the count is an asterisk (“*”), all remaining array elements will be converted. Any of the directives “sSiIlL” may be followed by an underscore (“_”) or exclamation mark (“!”) to use the underlying platform’s native size for the specified type; otherwise, they use a platform-independent size. Spaces are ignored in the template string. See also String#unpack.
a = [ "a", "b", "c" ] n = [ 65, 66, 67 ] a.pack("A3A3A3") #=> "a b c " a.pack("a3a3a3") #=> "a\000\000b\000\000c\000\000" n.pack("ccc") #=> "ABC"
Directives for pack.
Integer | Array |
Directive | Element | Meaning
---------------------------------------------------------------------------
C | Integer | 8-bit unsigned (unsigned char)
S | Integer | 16-bit unsigned, native endian (uint16_t)
L | Integer | 32-bit unsigned, native endian (uint32_t)
Q | Integer | 64-bit unsigned, native endian (uint64_t)
J | Integer | pointer width unsigned, native endian (uintptr_t)
| | (J is available since Ruby 2.3.)
| |
c | Integer | 8-bit signed (signed char)
s | Integer | 16-bit signed, native endian (int16_t)
l | Integer | 32-bit signed, native endian (int32_t)
q | Integer | 64-bit signed, native endian (int64_t)
j | Integer | pointer width signed, native endian (intptr_t)
| | (j is available since Ruby 2.3.)
| |
S_, S! | Integer | unsigned short, native endian
I, I_, I! | Integer | unsigned int, native endian
L_, L! | Integer | unsigned long, native endian
Q_, Q! | Integer | unsigned long long, native endian (ArgumentError
| | if the platform has no long long type.)
| | (Q_ and Q! is available since Ruby 2.1.)
J! | Integer | uintptr_t, native endian (same with J)
| | (J! is available since Ruby 2.3.)
| |
s_, s! | Integer | signed short, native endian
i, i_, i! | Integer | signed int, native endian
l_, l! | Integer | signed long, native endian
q_, q! | Integer | signed long long, native endian (ArgumentError
| | if the platform has no long long type.)
| | (q_ and q! is available since Ruby 2.1.)
j! | Integer | intptr_t, native endian (same with j)
| | (j! is available since Ruby 2.3.)
| |
S> L> Q> | Integer | same as the directives without ">" except
J> s> l> | | big endian
q> j> | | (available since Ruby 1.9.3)
S!> I!> | | "S>" is same as "n"
L!> Q!> | | "L>" is same as "N"
J!> s!> | |
i!> l!> | |
q!> j!> | |
| |
S< L< Q< | Integer | same as the directives without "<" except
J< s< l< | | little endian
q< j< | | (available since Ruby 1.9.3)
S!< I!< | | "S<" is same as "v"
L!< Q!< | | "L<" is same as "V"
J!< s!< | |
i!< l!< | |
q!< j!< | |
| |
n | Integer | 16-bit unsigned, network (big-endian) byte order
N | Integer | 32-bit unsigned, network (big-endian) byte order
v | Integer | 16-bit unsigned, VAX (little-endian) byte order
V | Integer | 32-bit unsigned, VAX (little-endian) byte order
| |
U | Integer | UTF-8 character
w | Integer | BER-compressed integer
Float | |
Directive | | Meaning
---------------------------------------------------------------------------
D, d | Float | double-precision, native format
F, f | Float | single-precision, native format
E | Float | double-precision, little-endian byte order
e | Float | single-precision, little-endian byte order
G | Float | double-precision, network (big-endian) byte order
g | Float | single-precision, network (big-endian) byte order
String | |
Directive | | Meaning
---------------------------------------------------------------------------
A | String | arbitrary binary string (space padded, count is width)
a | String | arbitrary binary string (null padded, count is width)
Z | String | same as ``a'', except that null is added with *
B | String | bit string (MSB first)
b | String | bit string (LSB first)
H | String | hex string (high nibble first)
h | String | hex string (low nibble first)
u | String | UU-encoded string
M | String | quoted printable, MIME encoding (see RFC2045)
m | String | base64 encoded string (see RFC 2045, count is width)
| | (if count is 0, no line feed are added, see RFC 4648)
P | String | pointer to a structure (fixed-length string)
p | String | pointer to a null-terminated string
Misc. | |
Directive | | Meaning
---------------------------------------------------------------------------
@ | --- | moves to absolute position
X | --- | back up a byte
x | --- | null byte
Return the list of all array-oriented instance variables.
Tries to convert obj into an array, using to_ary method. Returns the converted array or nil if obj cannot be converted for any reason. This method can be used to check if an argument is an array.
Array.try_convert([1]) #=> [1] Array.try_convert("1") #=> nil if tmp = Array.try_convert(arg) # the argument is an array elsif tmp = String.try_convert(arg) # the argument is a string end
Replaces the contents of self with the contents of other_ary, truncating or expanding if necessary.
a = [ "a", "b", "c", "d", "e" ] a.replace([ "x", "y", "z" ]) #=> ["x", "y", "z"] a #=> ["x", "y", "z"]
Returns self.
If called on a subclass of Array, converts the receiver to an Array object.
Returns the result of interpreting ary as an array of [key, value] pairs.
[[:foo, :bar], [1, 2]].to_h # => {:foo => :bar, 1 => 2}
Same as Array#each, but passes the index of the element instead of the element itself.
An Enumerator is returned if no block is given.
a = [ "a", "b", "c" ] a.each_index {|x| print x, " -- " }
produces:
0 -- 1 -- 2 --
Same as Array#each, but traverses self in reverse order.
a = [ "a", "b", "c" ] a.reverse_each {|x| print x, " " }
produces:
c b a
Returns the index of the first object in ary such that the object is == to obj.
If a block is given instead of an argument, returns the index of the first object for which the block returns true. Returns nil if no match is found.
See also Array#rindex.
An Enumerator is returned if neither a block nor argument is given.
a = [ "a", "b", "c" ] a.index("b") #=> 1 a.index("z") #=> nil a.index { |x| x == "b" } #=> 1
Sorts self in place using a set of keys generated by mapping the values in self through the given block.
If no block is given, an Enumerator is returned instead.
Deletes every element of self for which the given block evaluates to false.
See also Array#select!
If no block is given, an Enumerator is returned instead.
a = %w{ a b c d e f } a.keep_if { |v| v =~ /[aeiou]/ } #=> ["a", "e"]
Returns an array containing the elements in self corresponding to the given selector(s).
The selectors may be either integer indices or ranges.
See also Array#select.
a = %w{ a b c d e f } a.values_at(1, 3, 5) # => ["b", "d", "f"] a.values_at(1, 3, 5, 7) # => ["b", "d", "f", nil] a.values_at(-1, -2, -2, -7) # => ["f", "e", "e", nil] a.values_at(4..6, 3...6) # => ["e", "f", nil, "d", "e", "f"]
Deletes the element at the specified index, returning that element, or nil if the index is out of range.
See also Array#slice!
a = ["ant", "bat", "cat", "dog"] a.delete_at(2) #=> "cat" a #=> ["ant", "bat", "dog"] a.delete_at(99) #=> nil
Deletes every element of self for which block evaluates to true.
The array is changed instantly every time the block is called, not after the iteration is over.
See also Array#reject!
If no block is given, an Enumerator is returned instead.
scores = [ 97, 42, 75 ] scores.delete_if {|score| score < 80 } #=> [97]