列舉使用python3 dict字典方法功能-Python教學-PHP中文網

列舉使用python3 dict字典方法功能

高洛峰

發布： 2017-03-21 14:21:44

原創

1492 人瀏覽過

clear(清空字典內容)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
print(stu.clear())

#输出：None

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copy（拷貝字典）

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
stu2 = stu.copy()
print(stu2)

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fromkeys(指定一個列表，把列表中的值作為字典的key,產生一個字典)

name = [&#39;tom&#39;,&#39;lucy&#39;,&#39;sam&#39;]
print(dict.fromkeys(name))
print(dict.fromkeys(name,25))  #指定默认值

#输出：{&#39;tom&#39;: None, &#39;lucy&#39;: None, &#39;sam&#39;: None}
#     {&#39;tom&#39;: 25, &#39;lucy&#39;: 25, &#39;sam&#39;: 25}

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get(指定key，取得對應的值)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
print(stu.get(&#39;num2&#39;))

#输出：Lucy

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items(傳回由「鍵值對組成元素「的列表)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
print(stu.items())

#输出：dict_items([(&#39;num2&#39;, &#39;Lucy&#39;), (&#39;num3&#39;, &#39;Sam&#39;), (&#39;num1&#39;, &#39;Tom&#39;)])

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keys(取得字典所有的key)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
print(stu.keys())

#输出：dict_keys([&#39;num3&#39;, &#39;num1&#39;, &#39;num2&#39;])

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pop(取得指定key的value，並在字典中刪除)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
name = stu.pop(&#39;num2&#39;)
print(name,stu)

#输出：Lucy {&#39;num1&#39;: &#39;Tom&#39;, &#39;num3&#39;: &#39;Sam&#39;}

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popitem(隨機取得某個鍵值對，並在字典中刪除)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
name = stu.popitem()
print(name,stu)

#输出：(&#39;num2&#39;, &#39;Lucy&#39;) {&#39;num3&#39;: &#39;Sam&#39;, &#39;num1&#39;: &#39;Tom&#39;}

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setdefault(取得指定key的value，如果key不存在，則建立)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
name = stu.setdefault(&#39;num5&#39;)
print(name,stu)

#输出：None {&#39;num1&#39;: &#39;Tom&#39;, &#39;num2&#39;: &#39;Lucy&#39;, &#39;num5&#39;: None, &#39;num3&#39;: &#39;Sam&#39;}

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update(新增鍵- 值對到字典)

stu = {
    &#39;num1&#39;:&#39;Tom&#39;,
    &#39;num2&#39;:&#39;Lucy&#39;,
    &#39;num3&#39;:&#39;Sam&#39;,
}
stu.update({&#39;num4&#39;:&#39;Ben&#39;})
print(stu)

#输出：{&#39;num2&#39;: &#39;Lucy&#39;, &#39;num3&#39;: &#39;Sam&#39;, &#39;num1&#39;: &#39;Tom&#39;, &#39;num4&#39;: &#39;Ben&#39;}

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