راهنمای سریع متدهای آرایه در Ruby — از صفر تا صد

1arr = []
2arr2 = Array.new

1arr_with_stuff = ["value", "separated by comma"] 
2arr_with_stuff2 = Array.new(["a", "b", "c"])
3range_to_arr = (1..9).to_a

1arr = Array.new(5, " ")
2# -> [" ", " ", " ", " ", " "]

1arr = %w(cat dog mouse 1 2)
2# -> ["cat", "dog", "mouse", "1", "2"]

1arr = "this is a string”.split 
2arr # -> ["this", "is", "a", "string"] 
3"hey".split("") # -> ["h","e","y"]

1arr = %w(cat dog mouse)
2str = arr.join(", ")
3str # -> "cat, dog, mouse"
4str2 = arr.join
5str2 #-> "catdogmouse"

1arr = %w(cat dog mouse cow pig)
2arr.length # -> 5
3arr.size # -> 5

1arr[0] # -> "cat"
2arr[1] # -> "dog"
3arr[100] # -> nil

1arr.index("dog") # -> 1
2arr.index("asdaf") # -> nil

1arr[-1] # -> "pig"
2arr[-2] # -> "cow"
3arr[-100] # -> nil

1arr.fetch(0) # -> "cat"
2arr.fetch(-1) # -> "pig"
3arr.fetch(100) # -> raise a KeyError 
4arr.fetch(100, "nothing there") # -> "nothing there" 
5arr.fetch(100) { |key| "nothing at index #{key}" }
6# -> "nothing at index 100"

1arr = ["cat", "dog", "mouse", "cow", "pig"]
2arr[1,3] # -> ["dog", "mouse", "cow"]
3arr[1..3] # -> ["dog", "mouse", "cow"]
4arr[1...3] # -> ["dog", "mouse"]
5arr[1..-1] # -> ["dog", "mouse", "cow", "pig"]

1arr = %w(cat dog mouse)
2arr.include?("cat") # -> true   
3arr.include?("zzz") #-> false

1arr = %w(cat dog mouse)
2arr[0] = "lynx"
3arr # -> ["lynx", "dog", "mouse"]

1arr = %w(cat dog mouse)
2arr << "cobra" 
3# returns changed array
4# -> ["cat", "dog", "mouse", "cobra"]
5arr.push("crow") 
6# returns changed array
7# -> ["cat", "dog", "mouse", "cobra", "crow"]
8# push can take multiple, << can't 
9arr.push("cow", "bee")
10# returns changed array
11# -> ["cat", "dog", "mouse", "cobra", "crow", "cow", "bee"]

1arr = %w(cat dog mouse)
2arr.unshift("clam") 
3# returns changed array
4# -> ["clam", "cat", "dog", "mouse"]
5arr.unshift("cow", "bee")
6# returns changed array
7# -> ["cow", "bee", "clam", "cat", "dog", "mouse"]

1arr = %w(cat dog mouse)
2arr.insert(1, "cow")
3# returns changed array
4# -> ["cat", "cow", "dog", "mouse"]
5arr.insert(1, "bee", "pig")
6# returns changed array
7# -> ["cat", "bee", "pig", "cow", "dog", "mouse"]

1arr = %w(cat dog mouse)
2arr.delete("cat") 
3# -> returns "cat"
4arr # -> ["dog", "mouse"]
5arr.delete("cat") 
6# -> returns nil
7arr # -> ["dog", "mouse"]
8arr.delete("whaaa?") { "not found" }   
9# -> "not found"
10# leave original alone by subtracting arrays
11# also lets you delete more than one item
12arr = %w(cat dog mouse pig cow)
13arr2 = arr - ["cat", "mouse"]
14arr2 # -> ["dog", "pig", "cow"]
15arr # -> ["cat", "dog", "mouse", "pig", "cow"]

1arr = %w(cat dog mouse)
2arr.delete_at(0) # -> "cat"
3arr # -> ["dog", "mouse"]
4arr.delete_at(100) # -> nil

1arr = %w(cat dog mouse)
2arr.pop # -> "mouse"
3arr # -> ["cat", "dog"]
4arr.pop # -> "dog"
5arr.pop # -> "cat" 
6arr.pop # -> nil

1arr = %w(cat dog mouse)
2arr.shift # -> "cat"
3arr # -> ["dog", "mouse"]
4arr.shift # -> "dog" 
5arr.shift # -> "mouse"
6arr.shift # -> nil

1arr_num = [4,12,9,1]
2arr_alpha = %w(ba aa cb bb)
3arr_num.sort # -> [1, 4, 9, 12]
4arr_alpha.sort # -> ["aa", "ba", "bb", "cb,"]
5# permanently change original arr
6arr_num.sort!
7arr_alpha.sort!

1arr = %w(first mid last)
2arr.reverse # -> ["last", "mid", "first"]
3arr # -> ["first", "mid", "last"]
4# permanently change original arr
5arr.reverse!
6# useful for sorting in reverse order
7arr.sort.reverse

1arr = [1,2,3,4]
2arr.shuffle # -> [2, 1, 3, 4]
3arr # -> [1, 2, 3, 4]
4arr.shuffle! # -> [4, 2, 1, 3]
5arr # -> [4, 2, 1, 3]

1[1,2,3,4].sample # -> 1
2[1,2,3,4].sample # -> 3

1arr = %w(a b c)
2arr.each do |val| 
3  puts "value is #{x}"
4end 
5# will put each value but return:
6# ["a", "b", "c"]

1arr = %w(a b c)
2arr.each_with_index do |val, idx| 
3  puts “index #{idx}: #{val}” 
4end 
5# still returns:
6# ["a", "b", "c"]

1arr = %w(a b c)
2arr.each_with_object({}) do |value, result|
3  result[value] = value.upcase
4end
5# returns: 
6# {"a"=>"A", "b"=>"B", "c"=>"C"}

1arr = %w(a b c)
2arr
3  .each_with_index
4  .with_object({}) do |(value, idx), result|
5    result[value.to_sym] = "I was index #{idx}"
6  end
7# returns: 
8# {
9#   "a"=>"I was index 0", 
10#   "b"=>"I was index 1", 
11#   "c"=>"I was index 2"
12# }

1arr = %w(a b c) 
2arr2 = arr.map do |value| 
3  “#{value}!!” 
4end 
5arr2 # -> [ “a!!”, “b!!”, “c!!”]
6arr # ->[ “a”, “b”, “c” ]

1arr = %w(a b c) 
2arr.map! do |value| 
3  “#{value}!!” 
4end
5arr # -> [ “a!!”, “b!!”, “c!!”]

1arr = %w(a b c)
2arr.map.with_index do |value, idx|
3  "index #{idx} is '#{value}'"
4end
5#returns: 
6# [
7#   "index 0 is 'a'", 
8#   "index 1 is 'b'", 
9#   "index 2 is 'c'"
10# ]

1arr.empty? # returns true or false

1arr1 = [1, 2, 3]
2arr2 = [4, 5, 6]
3arr3 = [7, 8, 9]
4# leaves originals alone 
5arr1 + arr3 + arr2
6# returns: 
7# [1, 2, 3, 7, 8, 9, 4, 5, 6]
8# if you want to permanently alter original 
9# use concat
10arr1.concat(arr2)
11arr1 # -> [1, 2, 3, 4, 5, 6]

1arr = [1,2,3,4]   
2arr.any? do |num| 
3  num > 2   
4end      
5# returns true

1arr = [1,2,3,4]   
2arr.all? do |num| 
3  num < 100
4end      
5# returns true
6# check for the reverse with none?
7arr = [1,2,3,4]   
8arr.none? do |num| 
9  num < 100
10end
11# returns false

1[1, 2, 3, 4].find do |num| 
2  num.even? 
3end 
4# returns 2

1[1, 2, 3, 4].select do |num| 
2  num.even? 
3end 
4# returns [2, 4]

1[1, 2, 3, 4, 5, 6].count do |num| 
2  num.even? 
3end 
4# returns 3

1[1, 2, 3, 1, 2, 4].uniq 
2# returns [1, 2, 3, 4]
3[1, nil, 2, nil, 3].compact
4# returns [1, 2, 3]