デフォルト引数とキーワード引数

開発者向け中級 Python

Jasmin Ludolf

Senior Data Science Content Developer

Average

# Create a custom function
def average(values):
    # Calculate the average
    average_value = sum(values) / len(values)

    # Round the results
    rounded_average = round(average_value, 2)

    # Return rounded_average as an output
    return rounded_average

values = 引数

引数

関数またはメソッドに渡される値
- 位置引数
- キーワード因数

位置引数

順番にカンマで区切って渡す引数

# Round pi to 2 digits
print(round(3.1415926535, 2))

3.14

キーワード引数

keywords に値を割り当てて渡す引数
関数の解釈と引数の追跡に便利

# Round pi to 2 digits 
print(round(number=3.1415926535

キーワード引数

keywords に値を割り当てて渡す引数
関数の解釈と引数の追跡に便利

# Round pi to 2 digits 
print(round(number=3.1415926535, ndigits=2))

3.14

キーワード引数の識別

# Get more information about the help function
print(help(round))

Help on built-in function round in module builtins:

round(number, ndigits=None)
    Round a number to a given precision in decimal digits.

    The return value is an integer if ndigits is omitted or None.  Otherwise,
    the return value has the same type as the number.  ndigits may be negative.

キーワード引数

Help on built-in function round in module builtins:

round(number, ndigits=None)
  Round a number to a given precision in decimal digits.

  The return value is an integer if ndigits is omitted or None. Otherwise 
  the return value has the same type as the number. ndigits may be negative.

第1引数：number
第2引数：ndigits

デフォルト引数

Help on built-in function round in module builtins:

round(number, ndigits=None)
    Round a number to a given precision in decimal digits.

    The return value is an integer if ndigits is omitted or None.  Otherwise,
    the return value has the same type as the number.  ndigits may be negative.

None = 値なし／空
デフォルト引数：default値をargumentに設定する方法
None を 2 に上書きする
一般的な値 - デフォルト引数で設定

引数の追加

# Create a custom function
def average(values):
    average_value = sum(values) / len(values)
    rounded_average = round(average_value, 2)
    return rounded_average

引数の追加

# Create a custom function
def average(values, rounded=False):

引数の追加

# Create a custom function
def average(values, rounded=False):

    # Round average to two decimal places if rounded is True
    if rounded == True:

        average_value = sum(values) / len(values)
        rounded_average = round(average_value, 2)
        return rounded_average

引数の追加

# Create a custom function
def average(values, rounded=False):

    # Round average to two decimal places if rounded is True
    if rounded == True:
        average_value = sum(values) / len(values)
        rounded_average = round(average_value, 2)
        return rounded_average

    # Otherwise, don't round
    else:
        average_value = sum(values) / len(values)
        return average_value

修正した average() 関数を使用する

# List of preparation times (minutes)
preparation_times = [19.23, 15.67, 48.57, 23.45, 12.06, 34.56, 45.67]

修正した average() 関数を使用する

# Get the average without rounding
print(average(preparation_times, False))

28.4585714

# Get the average without rounding
print(average(preparation_times))

28.4585714

修正した average() 関数を使用する

# Get the rounded average
print(average(values=preparation_times, rounded=True))

28.46

練習しましょう！

開発者向け中級 Python