Python--推导式、函数、自定义函数

列表推导式

number_list = [number for number in range(1, 7)]
print(number_list)
------------------
[1, 2, 3, 4, 5, 6]

列表推导式加条件语句

• 单if

  number_list = [number
               for number in range(1, 7)
               if number % 2 == 0]
  print(number_list)
  ------------------
  [2, 4, 6]

  ---

• if else

  number_list = [number**2
               if number % 2 == 0
              else number+10
               for number in range(1, 7)]
  print(number_list)
  -----------------------
  [11, 4, 13, 16, 15, 36]

  ---

  几个函数

• split()

  • 将字符串进行拆分成一个一个单词
  • 无参数

  a = 'Hello world'
  b = a.split()
  print(b)
  ------------------
  ['Hello', 'world']

  • • 有1个参数

  a = 'Hello,world,I,am,coming'
  b = a.split(',')
  print(b)
  ---------------------------------------
  ['Hello', 'world', 'I', 'am', 'coming']

• • 有2个参数--->第一个为标记,第二个为切割几次

    a = 'Hello,world,I,am,coming'
    b = a.split(',',2)
    print(b)
    ---------------------------------
    ['Hello', 'world', 'I,am,coming']

    ---

    names = ['William Wang',
         'Tommy Zhao',
         'Jack Chen',
         'Mary Liu']
    first_name = [name.split()[0].lower()
              for name in names]
    print(first_name)
    ------------------------------------
    ['william', 'tommy', 'jack', 'mary']

    ---

    scores_card = {'Tom': 90, 'Jimmy': 85,
               'Kim': 40, 'William': 99,
               'Tommy': 61}
    passed = [name
          for name, score in scores_card.items()
          if score >= 60]
    print(passed)
    ------------------------------------
    ['Tom', 'Jimmy', 'William', 'Tommy']

    ---

自定义函数

• def 头部

  def add(num1, num2):
    result = num1 + num2
    return print(result)
  add(10, 11)
  -----------
  21

• • def----------------函数头部

    • add----------------函数名
    • (num1,num2)----函数引用参数

自定义函数默认参数

def add(num1, num2, super_num3 = 10000):
    result = (num1 + num2)*super_num3
    return print(result)
add(10, 11)
-----------
210000

• super_num3-—如果函数调用没有对第三个参数赋值,则默认使用参数默认值10000