Class: Array

Inherits:
Object show all
Defined in:
lib/webget_ruby_ramp/array.rb

Overview

Array extensions

Instance Method Summary collapse

Instance Method Details

#choice ⇒ Object

Return a random item from the array

Examples

[1,2,3,4].choice => 2
[1,2,3,4].choice => 4
[1,2,3,4].choice => 3

Implemented in Ruby 1.9



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# File 'lib/webget_ruby_ramp/array.rb', line 88

def choice
  self[Kernel.rand(size)]
end

#choices(count) ⇒ Object

Return a new array filled with count calls to choice

Examples

[1,2,3,4].choices(2) => [3,1]
[1,2,3,4].choices(3) => [4,2,3]



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# File 'lib/webget_ruby_ramp/array.rb', line 99

def choices(count)
  arr = Array.new
  count.times { arr << self.choice }
  return arr
end

#divvy(number_of_slices) ⇒ Object

Divvy the array, like a pie, into n number of slices.

If the array divides evenly, then each slice has size/n items.

Otherwise, divvy makes a best attempt by rounding up to give earlier slices one more item, which makes the last slice smaller:

Examples

[1,2,3,4,5].divvy(2) => [[1,2,3],[4,5]]
[1,2,3,4,5,6,7].divvy(3) => [[1,2,3],[4,5,6],[7]]

If the array size so small compared to n that there is no mathematical way to n slices, then divvy will return as many slices as it can.

Examples

[1,2,3,4,5,6].divvy(4) => [[1,2],[3,4],[5,6]]



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# File 'lib/webget_ruby_ramp/array.rb', line 172

def divvy(number_of_slices)
  (number_of_slices.is_a? Integer) or (raise ArgumentError, "number_of_slices must be an integer")
  (number_of_slices > 0) or (raise ArgumentError, "number_of_slices must be > 0")
  return slices((length.to_f/number_of_slices.to_f).ceil)
end

#intersect ⇒ Object

Return the intersection of the array’s items. In typical usage, each item is an array.

Examples

arr=[[1,2,3,4],[3,4,5,6]]
arr.intersect
=> [3,4]

Examples with proc

arr.map(&:foo).intersect
=> foos that are in all of the array items

Example with nil

[].intersect => []



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# File 'lib/webget_ruby_ramp/array.rb', line 220

def intersect
  inject{|inj,item| inj & item.to_a } || []
end

#join(*fixes) ⇒ Object

Concatenate the items into a string by join.

Typical Array#join with infix

list=['a','b','c']
list.join("*") => "a*b*c"

Improved join with infix, prefix, suffix

list=['a','b','c']
list.join("*","[","]") => "[a]*[b]*[c]"

Improved join with just prefix and suffix

list=['a','b','c']
list.join("[","]") => "[a][b][c]"



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# File 'lib/webget_ruby_ramp/array.rb', line 29

def join(*fixes)
  if fixes.is_a?(String) then return self.ruby_join(fixes) end
  case fixes.size
  when 0
    return self.ruby_join()
  when 1
    return self.ruby_join(fixes[0])
  when 2
    prefix=fixes[0].to_s
    suffix=fixes[1].to_s
    return self.map{|item| prefix + item.to_s + suffix}.ruby_join()
  when 3
    infix =fixes[0].to_s
    prefix=fixes[1].to_s
    suffix=fixes[2].to_s
    return self.map{|item| prefix + item.to_s + suffix}.ruby_join(infix)
  else
    raise ArgumentError, "join() takes 0-3 arguments; you gave #{fixes.size}]"
  end
end

#onto(values) ⇒ Object

Return a hash of this array’s items as keys mapped onto another array’s items as values.

Example

foo=[:a,:b,:c]
goo=[:x,:y,:z]
foo.onto(goo) => {:a=>:x, :b=>:y, :c=>:z}

This is identical to calling foo.zip(values).to_h



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# File 'lib/webget_ruby_ramp/array.rb', line 116

def onto(values)
  size==values.size or raise ArgumentError, "Array size #{size} must match values size #{size}" 
  zip(values).to_h
end

#rotate! ⇒ Object

Move the first item to the last by using Array#shift and Array#push

Examples

[1,2,3,4].rotate! => [2,3,4,1]
['a','b','c'].rotate! => ['b','c','a']
[].rotate! => []

Return self



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# File 'lib/webget_ruby_ramp/array.rb', line 71

def rotate!
  if size>0
    push item=shift
  end
  self
end

#ruby_join ⇒ Object

Alias join because we’re going to override it



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# File 'lib/webget_ruby_ramp/array.rb', line 12

alias :ruby_join :join

#shifted(number_of_items = 1) ⇒ Object Also known as: cdr, rest

Returns the rest of the items of self, after a shift.

Example

list=['a','b','c']
list.shift => 'a'
list.shifted => ['b','c']

Example with length

list.shifted(0) => ['a','b','c']
list.shifted(1) => ['b','c']
list.shifted(2) => ['c']
list.shifted(3) => []

Ruby programmers may prefer this alias wording:

list.first => 'a'
list.rest => ['b','c']

LISP programmers may prefer this alias wording:

list.car => 'a'
list.cdr => ['b','c']



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# File 'lib/webget_ruby_ramp/array.rb', line 254

def shifted(number_of_items=1)
  (number_of_items.is_a? Integer) or (raise ArgumentError, "number_of_items must be an integer")
  (number_of_items >= 0) or (raise ArgumentError, "number_of_items must be >= 0")
  slice(number_of_items,self.length-number_of_items)
end

#shifted!(number_of_items = 1) ⇒ Object Also known as: cdr!, rest!

Delete the first number_of_items items. Returns the array, not the deleted items.

Example

list=['a','b','c']
list.shifted!
list => ['b','c']

Example with length:

list=['a','b','c']
list.shifted!(2)
list => ['c']

If n is greater than the array size, then return []



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# File 'lib/webget_ruby_ramp/array.rb', line 279

def shifted!(number_of_items=1)
  (number_of_items.is_a? Integer) or (raise ArgumentError, "number_of_items must be an integer")
  (number_of_items >= 0) or (raise ArgumentError, "number_of_items must be >= 0")
  slice!(0,number_of_items)
  return self
end

#shuffle ⇒ Object

Return the array items in random order.

This implementation is optimized for speed, not for memory use. See codeidol.com/other/rubyckbk/Arrays/Shuffling-an-Array/

Example

list=
list=['a','b','c']
list.shuffle!
list => ['c','a','b']



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# File 'lib/webget_ruby_ramp/array.rb', line 319

def shuffle  
  dup.shuffle!  
end

#shuffle! ⇒ Object

Randomly arrange the array items.

This implementation is optimized for speed, not for memory use. See codeidol.com/other/rubyckbk/Arrays/Shuffling-an-Array/

Example

list=
list=['a','b','c']
list.shuffle!
list => ['c','a','b']



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# File 'lib/webget_ruby_ramp/array.rb', line 301

def shuffle!  
  each_index do |i| 
    j = rand(length-i) + i
    self[j], self[i] = self[i], self[j]  
  end
end

#size? ⇒ Boolean

Return true if size > 0

Examples

[1,2,3].size? => true
[].size? => false

Returns:

  • (Boolean) 


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# File 'lib/webget_ruby_ramp/array.rb', line 57

def size?
  return size>0
end

#slices(slice_length) ⇒ Object

Return items in groups of n items (aka slices)

Examples

[1,2,3,4,5,6,7,8].slices(2) => [[1,2],[3,4],[5,6],[7,8]]
[1,2,3,4,5,6,7,8].slices(4) => [[1,2,3,4],[5,6,7,8]]

If the slices don’t divide evenly, then the last is smaller.

Examples

[1,2,3,4,5,6,7,8].slices(3) => [[1,2,3],[4,5,6],[7,8]]
[1,2,3,4,5,6,7,8].slices(5) => [[1,2,3,4,5],[6,7,8]]



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# File 'lib/webget_ruby_ramp/array.rb', line 141

def slices(slice_length)
  (slice_length.is_a? Integer) or (raise ArgumentError, "slice_length must be an integer")
  (slice_length > 0) or (raise ArgumentError, "slice_length must be > 0")
  arr=[]
  index=0
  while index<length
    arr.push self[index...(index+slice_length)]
    index+=slice_length
  end
  return arr
end

#to_csv(ops = {}) ⇒ Object

Returns a CSV (Comma Separated Value) string of this array.

Example of a one-dimensional array

[1,2,3].to_csv => "1,2,3\n"

Example of a multi-dimensional array

[[1,2,3],[4,5,6]] => "1,2,3\n4,5,6\n"

Example of a blank array

[].to_csv => ""

N.b. this method uses the multi-dimensional if the array’s first item is also an array.



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# File 'lib/webget_ruby_ramp/array.rb', line 347

def to_csv(ops={})

  return "" if size==0

  generator = RUBY_VERSION >= "1.9" ? CSV : CSV::Writer

  str=''
  if size>0 and self[0].is_a?Array
    generator.generate(str) do |csv|
      self.each do |row|
        csv << row
      end
    end
  else
    generator.generate(str) do |csv|
      csv << self.map{|item| item.to_s}
    end
  end
  return str
end

#to_tsv(ops = {}) ⇒ Object Also known as: to_tdf

Returns a TSV (Tab Separated Value) string representation of a multi-dimensional array.

Each subarray becomes one ‘line’ in the output.

Example of a blank array

[].to_csv => ""



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# File 'lib/webget_ruby_ramp/array.rb', line 378

def to_tsv(ops={})
  self.map{|row| row.join("\t")+"\n"}.join
end

#union ⇒ Object

Return the union of the array’s items. In typical use, each item is an array.

Example using Ruby Array pipe

arr=[[1,2,3,4],[3,4,5,6]]
arr.union => [1,2,3,4,5,6]

Examples with proc

arr.map(&:foo).union
=> foos that are in any of the array items

Example with nil

[].union => []



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# File 'lib/webget_ruby_ramp/array.rb', line 200

def union
  inject{|inj,item| inj | item.to_a } || []
end