When called with positive Integer argument count and a block, calls the block with each element, then does so again, until it has done so count times; returns nil:
output = [] [0, 1].cycle(2) {|element| output.push(element) } # => nil output # => [0, 1, 0, 1]
If count is zero or negative, does not call the block:
[0, 1].cycle(0) {|element| fail 'Cannot happen' } # => nil [0, 1].cycle(-1) {|element| fail 'Cannot happen' } # => nil
When a block is given, and argument is omitted or nil, cycles forever:
# Prints 0 and 1 forever. [0, 1].cycle {|element| puts element } [0, 1].cycle(nil) {|element| puts element }
When no block is given, returns a new Enumerator:
[0, 1].cycle(2) # => #<Enumerator: [0, 1]:cycle(2)> [0, 1].cycle # => # => #<Enumerator: [0, 1]:cycle> [0, 1].cycle.first(5) # => [0, 1, 0, 1, 0]
Shuffles the elements of self in place.
a = [1, 2, 3] #=> [1, 2, 3] a.shuffle! #=> [2, 3, 1] a #=> [2, 3, 1]
The optional random argument will be used as the random number generator:
a.shuffle!(random: Random.new(1)) #=> [1, 3, 2]
Returns a new array with elements of self shuffled.
a = [1, 2, 3] #=> [1, 2, 3] a.shuffle #=> [2, 3, 1] a #=> [1, 2, 3]
The optional random argument will be used as the random number generator:
a.shuffle(random: Random.new(1)) #=> [1, 3, 2]
Returns random elements from self.
When no arguments are given, returns a random element from self:
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] a.sample # => 3 a.sample # => 8
If self is empty, returns nil.
When argument n is given, returns a new Array containing n random elements from self:
a.sample(3) # => [8, 9, 2] a.sample(6) # => [9, 6, 10, 3, 1, 4]
Returns no more than a.size elements (because no new duplicates are introduced):
a.sample(a.size * 2) # => [6, 4, 1, 8, 5, 9, 10, 2, 3, 7]
But self may contain duplicates:
a = [1, 1, 1, 2, 2, 3] a.sample(a.size * 2) # => [1, 1, 3, 2, 1, 2]
The argument n must be a non-negative numeric value. The order of the result array is unrelated to the order of self. Returns a new empty Array if self is empty.
The optional random argument will be used as the random number generator:
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] a.sample(random: Random.new(1)) #=> 6 a.sample(4, random: Random.new(1)) #=> [6, 10, 9, 2]
Returns true if self is an odd number, false otherwise.
Returns the argument (angle) for self in radians; see polar coordinates:
Complex.polar(3, Math::PI/2).arg # => 1.57079632679489660
If self was created with rectangular coordinates, the returned value is computed, and may be inexact:
Complex.polar(1, 1.0/3).arg # => 0.33333333333333326
Returns zero if self is positive, Math::PI otherwise.
Escapes str so that it can be safely used in a Bourne shell command line.
See Shellwords.shellescape for details.
Returns the count of characters (not bytes) in self:
'foo'.length # => 3 'тест'.length # => 4 'こんにちは'.length # => 5
Contrast with String#bytesize:
'foo'.bytesize # => 3 'тест'.bytesize # => 8 'こんにちは'.bytesize # => 15
Returns a printable version of self, enclosed in double-quotes, with special characters escaped, and with non-printing characters replaced by hexadecimal notation:
"hello \n ''".dump # => "\"hello \\n ''\"" "\f\x00\xff\\\"".dump # => "\"\\f\\x00\\xFF\\\\\\\"\""
Related: String#undump (inverse of String#dump).
Returns an array of the codepoints in self; each codepoint is the integer value for a character:
'hello'.codepoints # => [104, 101, 108, 108, 111] 'тест'.codepoints # => [1090, 1077, 1089, 1090] 'こんにちは'.codepoints # => [12371, 12435, 12395, 12385, 12399]
Returns a copy of self with characters specified by selectors removed (see Multiple Character Selectors):
"hello".delete "l","lo" #=> "heo" "hello".delete "lo" #=> "he" "hello".delete "aeiou", "^e" #=> "hell" "hello".delete "ej-m" #=> "ho"
Like String#delete, but modifies self in place. Returns self if any changes were made, nil otherwise.
Returns a frozen, possibly pre-existing copy of the string.
The returned String will be deduplicated as long as it does not have any instance variables set on it and is not a String subclass.
Note that -string variant is more convenient for defining constants:
FILENAME = -'config/database.yml'
while dedup is better suitable for using the method in chains of calculations:
@url_list.concat(urls.map(&:dedup))
Returns 0 if self is positive, Math::PI otherwise.
Returns the file descriptor used in dir.
d = Dir.new('..') d.fileno # => 8
This method uses the dirfd() function defined by POSIX 2008; the method is not implemented on non-POSIX platforms (raises NotImplementedError).
Removes the directory at dirpath from the underlying file system:
Dir.rmdir('foo') # => 0
Raises an exception if the directory is not empty.
Deletes the named files, returning the number of names passed as arguments. Raises an exception on any error. Since the underlying implementation relies on the unlink(2) system call, the type of exception raised depends on its error type (see linux.die.net/man/2/unlink) and has the form of e.g. Errno::ENOENT.
See also Dir::rmdir.
Returns true if the named file is readable by the effective user and group id of this process. See eaccess(3).
Note that some OS-level security features may cause this to return true even though the file is not readable by the effective user/group.
Returns true if the named file is writable by the effective user and group id of this process. See eaccess(3).
Note that some OS-level security features may cause this to return true even though the file is not writable by the effective user/group.
Returns true if the named file is executable by the effective user and group id of this process. See eaccess(3).
Windows does not support execute permissions separately from read permissions. On Windows, a file is only considered executable if it ends in .bat, .cmd, .com, or .exe.
Note that some OS-level security features may cause this to return true even though the file is not executable by the effective user/group.
Returns true if the named file exists and is a regular file.
file can be an IO object.
If the file argument is a symbolic link, it will resolve the symbolic link and use the file referenced by the link.