2.1.2.Python crash course

String

• print and format的方式

print('My number is: {one}, and my name is: {two}, more {one}'.format(one=num,two=name))

• concate

List, Tuple, Dictionary, Set

• List

  • 可讀可寫

    l = [1,2,3]
    item = l.pop()
    l.append('new')
    'x' in ['x', 'y', 'z'] //return True
    
    x = [(1, 2), (3, 4), (5, 6)]
    for a, b in x:
      print(a)
      print(b)

• Tuple

  • 只有初始化時可賦值

    t = (1,2,3)

• Dictionary

  • key可以是string或是number

    d = {'key1':'item1','key2':'item2'}
    d.keys()
    d.items()
    d.values()

• Set

  • 只會儲存唯一值

    In : {1,2,3,1,2,1,2,3,3,3,3,2,2,2,1,1,2}
    Out: {1, 2, 3}

Function

• 定義function

def my_func(param1='default'):
    """
    Docstring goes here.
    """
    print(param1)

Map

• 根據提供的函數對指定序列做映射

def times2(var):
    return var*2

seq = [1,2,3,4,5]
map(times2,seq)

lambda expressions

t = lambda var: var*2
t(2)

filter

• 以傳入的boolean function作為條件函式, iterate所有的sequence的元素並收集 function(元素) 為True的元素到一個List

seq = [1,2,3,4,5]
list(map(lambda var: var*2,seq))