When invoked with a block, yields all repeated 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 repeated combinations are yielded.
If no block is given, an Enumerator is returned instead.
Examples:
a = [1, 2, 3] a.repeated_combination(1).to_a #=> [[1], [2], [3]] a.repeated_combination(2).to_a #=> [[1,1],[1,2],[1,3],[2,2],[2,3],[3,3]] a.repeated_combination(3).to_a #=> [[1,1,1],[1,1,2],[1,1,3],[1,2,2],[1,2,3], # [1,3,3],[2,2,2],[2,2,3],[2,3,3],[3,3,3]] a.repeated_combination(4).to_a #=> [[1,1,1,1],[1,1,1,2],[1,1,1,3],[1,1,2,2],[1,1,2,3], # [1,1,3,3],[1,2,2,2],[1,2,2,3],[1,2,3,3],[1,3,3,3], # [2,2,2,2],[2,2,2,3],[2,2,3,3],[2,3,3,3],[3,3,3,3]] a.repeated_combination(0).to_a #=> [[]] # one combination of length 0
By using binary search, finds an index of a value from this array which meets the given condition in O(log n) where n is the size of the array.
It supports two modes, depending on the nature of the block. They are exactly the same as in the case of the bsearch method, with the only difference being that this method returns the index of the element instead of the element itself. For more details consult the documentation for bsearch.
Returns the list of private methods accessible to obj. If the all parameter is set to false, only those methods in the receiver will be listed.
Returns true if class is the class of obj, or if class is one of the superclasses of obj or modules included in obj.
module M; end class A include M end class B < A; end class C < B; end b = B.new b.is_a? A #=> true b.is_a? B #=> true b.is_a? C #=> false b.is_a? M #=> true b.kind_of? A #=> true b.kind_of? B #=> true b.kind_of? C #=> false b.kind_of? M #=> true
Returns the factorization of self.
See Prime#prime_division for more details.
Iterates the given block over all prime numbers.
See Prime#each for more details.
Returns the number of bits of the value of int.
“Number of bits” means the bit position of the highest bit which is different from the sign bit (where the least significant bit has bit position 1). If there is no such bit (zero or minus one), zero is returned.
I.e. this method returns ceil(log2(int < 0 ? -int : int+1)).
(-2**1000-1).bit_length #=> 1001 (-2**1000).bit_length #=> 1000 (-2**1000+1).bit_length #=> 1000 (-2**12-1).bit_length #=> 13 (-2**12).bit_length #=> 12 (-2**12+1).bit_length #=> 12 -0x101.bit_length #=> 9 -0x100.bit_length #=> 8 -0xff.bit_length #=> 8 -2.bit_length #=> 1 -1.bit_length #=> 0 0.bit_length #=> 0 1.bit_length #=> 1 0xff.bit_length #=> 8 0x100.bit_length #=> 9 (2**12-1).bit_length #=> 12 (2**12).bit_length #=> 13 (2**12+1).bit_length #=> 13 (2**1000-1).bit_length #=> 1000 (2**1000).bit_length #=> 1001 (2**1000+1).bit_length #=> 1001
This method can be used to detect overflow in Array#pack as follows:
if n.bit_length < 32 [n].pack("l") # no overflow else raise "overflow" end
Invokes the child class’s to_i method to convert num to an integer.
1.0.class #=> Float 1.0.to_int.class #=> Integer 1.0.to_i.class #=> Integer
Returns the float truncated to an Integer.
1.2.to_i #=> 1 (-1.2).to_i #=> -1
Note that the limited precision of floating point arithmetic might lead to surprising results:
(0.3 / 0.1).to_i #=> 2 (!)
Returns true if the named file is writable by the real user and group id of this process. See access(3)
If file_name is writable by others, returns an integer representing the file permission bits of file_name. Returns nil otherwise. The meaning of the bits is platform dependent; on Unix systems, see stat(2).
file_name can be an IO object.
File.world_writable?("/tmp") #=> 511 m = File.world_writable?("/tmp") sprintf("%o", m) #=> "777"
Returns the list of available encoding names.
Encoding.name_list
#=> ["US-ASCII", "ASCII-8BIT", "UTF-8",
"ISO-8859-1", "Shift_JIS", "EUC-JP",
"Windows-31J",
"BINARY", "CP932", "eucJP"]
Returns default internal encoding. Strings will be transcoded to the default internal encoding in the following places if the default internal encoding is not nil:
File data read from disk
Strings returned from Readline
Strings returned from SDBM
Values from ENV
Values in ARGV including $PROGRAM_NAME
Additionally String#encode and String#encode! use the default internal encoding if no encoding is given.
The locale encoding (__ENCODING__), not default_internal, is used as the encoding of created strings.
Encoding::default_internal is initialized by the source file’s internal_encoding or -E option.
Sets default internal encoding or removes default internal encoding when passed nil. You should not set Encoding::default_internal in ruby code as strings created before changing the value may have a different encoding from strings created after the change. Instead you should use ruby -E to invoke ruby with the correct default_internal.
See Encoding::default_internal for information on how the default internal encoding is used.
Iterates the given block for each element with an index, which starts from offset. If no block is given, returns a new Enumerator that includes the index, starting from offset
offset
the starting index to use
Returns any backtrace associated with the exception. This method is similar to Exception#backtrace, but the backtrace is an array of Thread::Backtrace::Location.
Now, this method is not affected by Exception#set_backtrace().
Sets the backtrace information associated with exc. The backtrace must be an array of String objects or a single String in the format described in Exception#backtrace.
Return a list of the local variable names defined where this NameError exception was raised.
Internal use only.
Return true if the caused method was called as private.
Callback invoked whenever the receiver is included in another module or class. This should be used in preference to Module.append_features if your code wants to perform some action when a module is included in another.
module A def A.included(mod) puts "#{self} included in #{mod}" end end module Enumerable include A end # => prints "A included in Enumerable"
Returns the list of modules included in mod.
module Mixin end module Outer include Mixin end Mixin.included_modules #=> [] Outer.included_modules #=> [Mixin]
Creates instance variables and corresponding methods that return the value of each instance variable. Equivalent to calling “attr:name” on each name in turn. String arguments are converted to symbols.
Defines a named attribute for this module, where the name is symbol.id2name, creating an instance variable (@name) and a corresponding access method to read it. Also creates a method called name= to set the attribute. String arguments are converted to symbols.
module Mod attr_accessor(:one, :two) end Mod.instance_methods.sort #=> [:one, :one=, :two, :two=]
Checks for a constant with the given name in mod. If inherit is set, the lookup will also search the ancestors (and Object if mod is a Module).
The value of the constant is returned if a definition is found, otherwise a NameError is raised.
Math.const_get(:PI) #=> 3.14159265358979
This method will recursively look up constant names if a namespaced class name is provided. For example:
module Foo; class Bar; end end Object.const_get 'Foo::Bar'
The inherit flag is respected on each lookup. For example:
module Foo class Bar VAL = 10 end class Baz < Bar; end end Object.const_get 'Foo::Baz::VAL' # => 10 Object.const_get 'Foo::Baz::VAL', false # => NameError
If the argument is not a valid constant name a NameError will be raised with a warning “wrong constant name”.
Object.const_get 'foobar' #=> NameError: wrong constant name foobar