update python_base.py
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59287d8b4b
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d1a5a5a905
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@ -254,7 +254,7 @@
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#-- 常用字典常量和操作
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D = {}
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D = {'spam':2, 'tol':{'ham':1}} # 嵌套字典
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D = dict.fromkeys(['s', 'd'], 8) # {'d': 8, 's': 8}
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D = dict.fromkeys(['s', 'd'], 8) # {'s': 8, 'd': 8}
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D = dict(name = 'tom', age = 12) # {'age': 12, 'name': 'tom'}
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D = dict([('name', 'tom'), ('age', 12)]) # {'age': 12, 'name': 'tom'}
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D = dict(zip(['name', 'age'], ['tom', 12])) # {'age': 12, 'name': 'tom'}
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@ -270,8 +270,8 @@
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# 字典注意事项:(1)对新索引赋值会添加一项(2)字典键不一定非得是字符串,也可以为任何的不可变对象
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#-- 字典解析
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D = {k:8 for k in ['s', 'd']} # {'d': 8, 's': 8}
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D = {k:v for (k, v) in zip(['name', 'age'], ['tom', 12])}
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D = {k:8 for k in ['s', 'd']} # {'s': 8, 'd': 8}
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D = {k:v for (k, v) in zip(['name', 'age'], ['tom', 12])} # {'age': 12, 'name': tom}
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#-- 字典的特殊方法__missing__:当查找找不到key时,会执行该方法
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class Dict(dict):
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@ -335,8 +335,8 @@
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#-- 序列赋值 序列解包
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[a, b, c] = (1, 2, 3) # a = 1, b = 2, c = 3
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a, b, c, d = "spam" # a = 's', b = 'p'
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a, b, c = range(3) # a = 0, b = 1
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a, b, c, d = "spam" # a = 's', b = 'p', c = 'a', d = 'm'
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a, b, c = range(3) # a = 0, b = 1, c = 2
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a, *b = [1, 2, 3, 4] # a = 1, b = [2, 3, 4]
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*a, b = [1, 2, 3, 4] # a = [1, 2, 3], b = 4
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a, *b, c = [1, 2, 3, 4] # a = 1, b = [2, 3], c = 4
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