一、字典

1、字典的初始化

字典是一種key-value結構

In [160]: d = {}

In [161]: type(d)
Out[161]: dict


In [166]: d = {‘a‘:1, ‘b‘:2}

In [167]: d
Out[167]: {‘a‘: 1, ‘b‘: 2}

In [180]: d = dict({"a":0, "b":1})

In [181]: d
Out[181]: {‘a‘: 0, ‘b‘: 1}


In [164]: d = dict([["a", 1], ["b", 2]])   #　可叠代對象的元素必須是一個二元組

In [165]: d
Out[165]: {‘a‘: 1, ‘b‘: 2}


In [168]: d = dict.fromkeys(range(5))　　　# 傳入的可叠代元素為key,值為None

In [169]: d
Out[169]: {0: None, 1: None, 2: None, 3: None, 4: None}

In [170]: d = dict.fromkeys(range(5), "abc")  # 傳入的可叠代元素為key,值為abc

In [171]: d
Out[171]: {0: ‘abc‘, 1: ‘abc‘, 2: ‘abc‘, 3: ‘abc‘, 4: ‘abc‘}

二、字典的基本操作

1、增

In [173]: d = {‘a‘:1, ‘b‘:2}     # 直接使用key做為索引，對某個不存在的索引賦值會增加KV對

In [174]: d["c"] = 1

In [175]: d
Out[175]: {‘a‘: 1, ‘b‘: 2, ‘c‘: 1}

In [175]: d
Out[175]: {‘a‘: 1, ‘b‘: 2, ‘c‘: 1}

In [176]: d["b"] = 1

In [177]: d
Out[177]: {‘a‘: 1, ‘b‘: 1, ‘c‘: 1}


## dict.update()

In [178]: d.update((("d", 4),("e", 5)))

In [179]: d
Out[179]: {‘a‘: 1, ‘b‘: 1, ‘c‘: 1, ‘d‘: 4, ‘e‘: 5}

【Python】11、python內置數據結構之字典