This gem is not object oriented. Please use this gem to make classes

A gem to change an array of chords from one key to any other key

###Installation $ gem install key_change

require 'key_change'

chords = ["G", "D/F#", "Em", "C", "D"]
old_key = "G"
new_key = "A"

# Declare a new array of chords with the function
new_chords = change(chords, old_key, new_key, :default)

The output is:

["A", "E/G♯", "F♯m", "D", "E"]

##Writing sharps and flats

# To make a sharp chord, write a pound sign
# It will be converted to "♯"
old_key = "F#"

# To make a flat chord, write a lowercase "b"
# It will be converted to "♭"
new_key = "Ab"

##Key change options As seen in the function, the last argument is an option. There are 4 options that can be chosen from

:sharp # This is the same as :default
:flat
:all_sharp
:all_flat

The option decides how the chords will be changed. ###Option 1 (:sharp)

chords = ["G", "Gb", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :sharp)
# The output is ["A", "A♭", "F♯m", "D"]
# Any chord that was originally flat will stay flat if applicable
# In any other case, they will become sharp (Like "F♯m")

###Option 2 (:flat)

chords = ["G", "F♯", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :flat)
# The output is ["A", "G♯", "G♭m", "D"]
# Any chord that was originally sharp will stay sharp if applicable
# In any other case, they will become flat (Like "G♭m")

###Option 3 (:all_sharp)

chords = ["G", "Gb", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :all_sharp)
# The output is ["A", "G♯", "F♯m", "D"]
# All applicable chords will be changed into sharps

###Option 4 (:all_flat)

chords = ["G", "Gb", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :all_sharp)
# The output is ["A", "A♭", "G♭m", "D"]
# All applicable chords will be changed into flats

##Supported chords The following chords are supported:

# Any of these can be added at the end of a chord or key
# for example: "Am7"
"dim7"
"dim"
"2"
"sus4"
"sus"
"maj7"
"maj"
"m7"
"m"
"7"
"6"
"9"
"aug"
"11"

##Not yet Haven't put these chords in yet:

"add2"
"add9"

key_change：歌のコードを楽に転調するためのgem

このgemはクラスが実装していません（オブジェクト指向なし）

。クラスインスタンス変数などを作るにはこちらの方をお使いください。

歌の（配列としての）コード、歌のキーと転調するための新しいキー、そしてどんな風に転調されるかを決めるオプション（4つの引数）をメソッドに渡すことで、歌の転調を楽に行うことができます。

###インストール $ gem install key_change

require 'key_change'

chords = ["G", "D/F#", "Em", "C", "D"]
old_key = "G"
new_key = "A"

# change()メソッドで新しい配列を定義します
new_chords = change(chords, old_key, new_key, :default)

出力されるのは：

["A", "E/G♯", "F♯m", "D", "E"]

##シャープやフラット記号

# シャープ記号を書くには、コメントで使う"#"を書きます
# "♯"に変換されます
old_key = "F#"

# フラット記号を書くには、小文字の"b"を書きます
# "♭"に変換されます
new_key = "Ab"

##転調のオプション change()メソッドの最後の引数はオプションです。 4つのオプションから選べます。

:sharp # これは「:default」と同じです
:flat
:all_sharp
:all_flat

###「:sharp」オプション

chords = ["G", "Gb", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :sharp)
# 出力されるのは["A", "A♭", "F♯m", "D"]です
# 元々はフラットであったコードはそのままフラットに変換されます
# それ以外のコードはシャープに変換されます（「F♯m」みたいに）

###「:flat」オプション

chords = ["G", "F♯", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :flat)
# 出力されるのは["A", "G♯", "G♭m", "D"]です
# 元々はシャープであったコードはそのままシャープに変換されます
# それ以外のコードはフラットに変換されます（「G♭m」みたいに）

###「:all_sharp」オプション

chords = ["G", "Gb", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :all_sharp)
# 出力されるのは["A", "G♯", "F♯m", "D"]です
# 対象となるコードは全部シャープに変換されます

###「:all_flat」オプション

chords = ["G", "Gb", "Em", "C"]
original_key = "G"
new_key = "A"

new_chords = change(chords, old_key, new_key, :all_sharp)
# 出力されるのは["A", "A♭", "G♭m", "D"]です
# 対象となるコードは全部フラットに変換されます

##使用可能なコード 下記のコードは使用できます：

# コードやキーの語尾として追加できます
# 例えば: "Am7"
"dim7"
"dim"
"2"
"sus4"
"sus"
"maj7"
"maj"
"m7"
"m"
"7"
"6"
"9"
"aug"
"11"

##まだ 下記のadditionはまだコードに入っていません：

"add2"
"add9"