Results for: "match"

Returns the element with the maximum element according to a given criterion. The ordering of equal elements is indeterminate and may be unstable.

With no argument and no block, returns the maximum element, using the elements’ own method <=> for comparison:

(1..4).max                   # => 4
(-4..-1).max                 # => -1
%w[d c b a].max              # => "d"
{foo: 0, bar: 1, baz: 2}.max # => [:foo, 0]
[].max                       # => nil

With positive integer argument n given, and no block, returns an array containing the first n maximum elements that exist:

(1..4).max(2)                   # => [4, 3]
(-4..-1).max(2)                # => [-1, -2]
%w[d c b a].max(2)              # => ["d", "c"]
{foo: 0, bar: 1, baz: 2}.max(2) # => [[:foo, 0], [:baz, 2]]
[].max(2)                       # => []

With a block given, the block determines the maximum elements. The block is called with two elements a and b, and must return:

• A negative integer if a < b.

• Zero if a == b.

• A positive integer if a > b.

With a block given and no argument, returns the maximum element as determined by the block:

%w[xxx x xxxx xx].max {|a, b| a.size <=> b.size } # => "xxxx"
h = {foo: 0, bar: 1, baz: 2}
h.max {|pair1, pair2| pair1[1] <=> pair2[1] }     # => [:baz, 2]
[].max {|a, b| a <=> b }                          # => nil

With a block given and positive integer argument n given, returns an array containing the first n maximum elements that exist, as determined by the block.

%w[xxx x xxxx xx].max(2) {|a, b| a.size <=> b.size } # => ["xxxx", "xxx"]
h = {foo: 0, bar: 1, baz: 2}
h.max(2) {|pair1, pair2| pair1[1] <=> pair2[1] }
# => [[:baz, 2], [:bar, 1]]
[].max(2) {|a, b| a <=> b }                          # => []

Related: min, minmax, max_by.

Returns a 2-element array containing the minimum and maximum elements according to a given criterion. The ordering of equal elements is indeterminate and may be unstable.

With no argument and no block, returns the minimum and maximum elements, using the elements’ own method <=> for comparison:

(1..4).minmax                   # => [1, 4]
(-4..-1).minmax                 # => [-4, -1]
%w[d c b a].minmax              # => ["a", "d"]
{foo: 0, bar: 1, baz: 2}.minmax # => [[:bar, 1], [:foo, 0]]
[].minmax                       # => [nil, nil]

With a block given, returns the minimum and maximum elements as determined by the block:

%w[xxx x xxxx xx].minmax {|a, b| a.size <=> b.size } # => ["x", "xxxx"]
h = {foo: 0, bar: 1, baz: 2}
h.minmax {|pair1, pair2| pair1[1] <=> pair2[1] }
# => [[:foo, 0], [:baz, 2]]
[].minmax {|a, b| a <=> b }                          # => [nil, nil]

Related: min, max, minmax_by.

Each element in the returned enumerator is a 2-element array consisting of:

• A value returned by the block.

• An array (“chunk”) containing the element for which that value was returned, and all following elements for which the block returned the same value:

So that:

• Each block return value that is different from its predecessor begins a new chunk.

• Each block return value that is the same as its predecessor continues the same chunk.

Example:

e = (0..10).chunk {|i| (i / 3).floor } # => #<Enumerator: ...>
# The enumerator elements.
e.next # => [0, [0, 1, 2]]
e.next # => [1, [3, 4, 5]]
e.next # => [2, [6, 7, 8]]
e.next # => [3, [9, 10]]

Method chunk is especially useful for an enumerable that is already sorted. This example counts words for each initial letter in a large array of words:

# Get sorted words from a web page.
url = 'https://raw.githubusercontent.com/eneko/data-repository/master/data/words.txt'
words = URI::open(url).readlines
# Make chunks, one for each letter.
e = words.chunk {|word| word.upcase[0] } # => #<Enumerator: ...>
# Display 'A' through 'F'.
e.each {|c, words| p [c, words.length]; break if c == 'F' }

Output:

["A", 17096]
["B", 11070]
["C", 19901]
["D", 10896]
["E", 8736]
["F", 6860]

You can use the special symbol :_alone to force an element into its own separate chuck:

a = [0, 0, 1, 1]
e = a.chunk{|i| i.even? ? :_alone : true }
e.to_a # => [[:_alone, [0]], [:_alone, [0]], [true, [1, 1]]]

For example, you can put each line that contains a URL into its own chunk:

pattern = /http/
open(filename) { |f|
  f.chunk { |line| line =~ pattern ? :_alone : true }.each { |key, lines|
    pp lines
  }
}

You can use the special symbol :_separator or nil to force an element to be ignored (not included in any chunk):

a = [0, 0, -1, 1, 1]
e = a.chunk{|i| i < 0 ? :_separator : true }
e.to_a # => [[true, [0, 0]], [true, [1, 1]]]

Note that the separator does end the chunk:

a = [0, 0, -1, 1, -1, 1]
e = a.chunk{|i| i < 0 ? :_separator : true }
e.to_a # => [[true, [0, 0]], [true, [1]], [true, [1]]]

For example, the sequence of hyphens in svn log can be eliminated as follows:

sep = "-"*72 + "\n"
IO.popen("svn log README") { |f|
  f.chunk { |line|
    line != sep || nil
  }.each { |_, lines|
    pp lines
  }
}
#=> ["r20018 | knu | 2008-10-29 13:20:42 +0900 (Wed, 29 Oct 2008) | 2 lines\n",
#    "\n",
#    "* README, README.ja: Update the portability section.\n",
#    "\n"]
#   ["r16725 | knu | 2008-05-31 23:34:23 +0900 (Sat, 31 May 2008) | 2 lines\n",
#    "\n",
#    "* README, README.ja: Add a note about default C flags.\n",
#    "\n"]
#   ...

Paragraphs separated by empty lines can be parsed as follows:

File.foreach("README").chunk { |line|
  /\A\s*\z/ !~ line || nil
}.each { |_, lines|
  pp lines
}

Returns an enumerator object generated from this enumerator and given enumerables.

e = (1..3).chain([4, 5])
e.to_a #=> [1, 2, 3, 4, 5]

Computes the arctangent of decimal to the specified number of digits of precision, numeric.

If decimal is NaN, returns NaN.

BigMath.atan(BigDecimal('-1'), 16).to_s
#=> "-0.785398163397448309615660845819878471907514682065e0"

Returns the state of the coverage measurement.

Allocate size bytes of memory and return the integer memory address for the allocated memory.

Returns a String containing the generated JSON data.

See also JSON.fast_generate, JSON.pretty_generate.

Argument obj is the Ruby object to be converted to JSON.

Argument opts, if given, contains a Hash of options for the generation. See Generating Options.

When obj is an Array, returns a String containing a JSON array:

obj = ["foo", 1.0, true, false, nil]
json = JSON.generate(obj)
json # => '["foo",1.0,true,false,null]'

When obj is a Hash, returns a String containing a JSON object:

obj = {foo: 0, bar: 's', baz: :bat}
json = JSON.generate(obj)
json # => '{"foo":0,"bar":"s","baz":"bat"}'

For examples of generating from other Ruby objects, see Generating JSON from Other Objects.

Raises an exception if any formatting option is not a String.

Raises an exception if obj contains circular references:

a = []; b = []; a.push(b); b.push(a)
# Raises JSON::NestingError (nesting of 100 is too deep):
JSON.generate(a)

Checks the status of the child process specified by pid. Returns nil if the process is still alive.

If the process is not alive, and raise was true, a PTY::ChildExited exception will be raised. Otherwise it will return a Process::Status instance.

pid

The process id of the process to check

raise

If true and the process identified by pid is no longer alive a PTY::ChildExited is raised.

Returns the log priority mask in effect. The mask is not reset by opening or closing syslog.

Sets the log priority mask. A method LOG_UPTO is defined to make it easier to set mask values. Example:

Syslog.mask = Syslog::LOG_UPTO(Syslog::LOG_ERR)

Alternatively, specific priorities can be selected and added together using binary OR. Example:

Syslog.mask = Syslog::LOG_MASK(Syslog::LOG_ERR) | Syslog::LOG_MASK(Syslog::LOG_CRIT)

The priority mask persists through calls to open() and close().

Compresses the given string. Valid values of level are Zlib::NO_COMPRESSION, Zlib::BEST_SPEED, Zlib::BEST_COMPRESSION, Zlib::DEFAULT_COMPRESSION, or an integer from 0 to 9.

This method is almost equivalent to the following code:

def deflate(string, level)
  z = Zlib::Deflate.new(level)
  dst = z.deflate(string, Zlib::FINISH)
  z.close
  dst
end

See also Zlib.inflate

Decompresses string. Raises a Zlib::NeedDict exception if a preset dictionary is needed for decompression.

This method is almost equivalent to the following code:

def inflate(string)
  zstream = Zlib::Inflate.new
  buf = zstream.inflate(string)
  zstream.finish
  zstream.close
  buf
end

See also Zlib.deflate

Returns true if the named file is a character device.

file_name can be an IO object.

Returns a Hash containing information about the GC.

The contents of the hash are implementation specific and may change in the future without notice.

The hash includes information about internal statistics about GC such as:

count

The total number of garbage collections ran since application start (count includes both minor and major garbage collections)

heap_allocated_pages

The total number of ‘:heap_eden_pages` + `:heap_tomb_pages`

heap_sorted_length

The number of pages that can fit into the buffer that holds references to all pages

heap_allocatable_pages

The total number of pages the application could allocate without additional GC

heap_available_slots

The total number of slots in all ‘:heap_allocated_pages`

heap_live_slots

The total number of slots which contain live objects

heap_free_slots

The total number of slots which do not contain live objects

heap_final_slots

The total number of slots with pending finalizers to be run

heap_marked_slots

The total number of objects marked in the last GC

heap_eden_pages

The total number of pages which contain at least one live slot

heap_tomb_pages

The total number of pages which do not contain any live slots

total_allocated_pages

The cumulative number of pages allocated since application start

total_freed_pages

The cumulative number of pages freed since application start

total_allocated_objects

The cumulative number of objects allocated since application start

total_freed_objects

The cumulative number of objects freed since application start

malloc_increase_bytes

Amount of memory allocated on the heap for objects. Decreased by any GC

malloc_increase_bytes_limit

When ‘:malloc_increase_bytes` crosses this limit, GC is triggered

minor_gc_count

The total number of minor garbage collections run since process start

major_gc_count

The total number of major garbage collections run since process start

remembered_wb_unprotected_objects

The total number of objects without write barriers

remembered_wb_unprotected_objects_limit

When ‘:remembered_wb_unprotected_objects` crosses this limit, major GC is triggered

old_objects

Number of live, old objects which have survived at least 3 garbage collections

old_objects_limit

When ‘:old_objects` crosses this limit, major GC is triggered

oldmalloc_increase_bytes

Amount of memory allocated on the heap for objects. Decreased by major GC

oldmalloc_increase_bytes_limit

When ‘:old_malloc_increase_bytes` crosses this limit, major GC is triggered

If the optional argument, hash, is given, it is overwritten and returned. This is intended to avoid probe effect.

This method is only expected to work on CRuby.

Returns true if new is newer than all old_list. Non-existent files are older than any file.

FileUtils.uptodate?('hello.o', %w(hello.c hello.h)) or \
    system 'make hello.o'

Returns true if new is newer than all old_list. Non-existent files are older than any file.

FileUtils.uptodate?('hello.o', %w(hello.c hello.h)) or \
    system 'make hello.o'

Changes permission bits on the named files (in list) to the bit pattern represented by mode.

mode is the symbolic and absolute mode can be used.

Absolute mode is

FileUtils.chmod 0755, 'somecommand'
FileUtils.chmod 0644, %w(my.rb your.rb his.rb her.rb)
FileUtils.chmod 0755, '/usr/bin/ruby', verbose: true

Symbolic mode is

FileUtils.chmod "u=wrx,go=rx", 'somecommand'
FileUtils.chmod "u=wr,go=rr", %w(my.rb your.rb his.rb her.rb)
FileUtils.chmod "u=wrx,go=rx", '/usr/bin/ruby', verbose: true

“a”

is user, group, other mask.

“u”

is user’s mask.

“g”

is group’s mask.

“o”

is other’s mask.

“w”

is write permission.

“r”

is read permission.

“x”

is execute permission.

“X”

is execute permission for directories only, must be used in conjunction with “+”

“s”

is uid, gid.

“t”

is sticky bit.

“+”

is added to a class given the specified mode.

“-”

Is removed from a given class given mode.

“=”

Is the exact nature of the class will be given a specified mode.