Ruby 配列 - masuyama's notes

Ruby 配列

#Ruby #array

code:rb

fruits = "apple", "banana", "cherry"

# 要素の取得（インデックスは0始まり）

fruits1 #=> "banana"

fruits-1 #=> "cherry"

fruits.first #=> "apple"

fruits.last(2) #=> "banana", "cherry"

# 要素を追加・上書き

fruits3 = "orange" #=> "apple", "banana", "cherry", "orange"

要素追加

code:rb

fruits = "apple", "banana", "cherry"

# 配列の末尾に1要素追加

fruits << "grape" #=> "apple", "banana", "cherry", "grape"

# 他の書き方

fruits.push("grage")

# pushなら複数追加も可能

fruits.push("orange", "grape") #=> "apple", "banana", "cherry", "orange", "grape"

# 配列の先頭に追加

fruits.unshift("peach") #=> "peach", "apple", "banana", "cherry"

要素削除

code:rb

fruits = "apple", "banana", "cherry"

# 配列末尾の要素を削除

fruits.pop #=> "cherry"

# 配列先頭の要素を削除

fruits.shift #=> "apple"

# インデックスを指定して削除

fruits.delete_at(1) #=> "banana"

# 値を指定して削除

fruits.delete("apple") #=> "apple"

# 条件を指定して削除

fruits.delete_if { |fruit| fruit.length <= 5 } #=> "banana", "cherry"

splat展開

code:rb

ary = 2, 3

1.push(ary) #=> [1, 2, 3]

1.push(*ary) #=> 1, 2, 3

*1..20

#=> 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20

code:rb

ary = "a", "b", "c", "d", "e", "f"

ary1..3 #=> "b", "c", "d"

# aryインデックス番号, 個数で要素取得

ary2, 3 #=> "c", "d", "e"

# 置き換え

ary2, 3 = "x" #=> "x"

ary #=> "a", "b", "x", "f"