keys_view=fruit_dict.keys()values_view=fruit_dict.values()items_view=fruit_dict.items()print(list(keys_view))# 输出:['apple', 'grape']print(list(values_view))# 输出:[3, 5]print(list(items_view))# 输出:[('apple', 3), ('grape', 5)] 3.1.2 get()方法 安全地获取键对应的值,当...
Otherwise, you can end up with a dictionary that maps keys to values incorrectly.Using the .fromkeys() Class MethodThe dict data type has a class method called .fromkeys() that lets you create new dictionaries from an iterable of keys and a default value. The method’s signature looks ...
为防止程序中断,可使用dict.get(key, default)方法或字典的setdefault(key, default)方法。前者返回default值(如果键不存在),后者则将default值存入字典。 data = {'name': 'Alice'} # 使用 get 方法安全访问 age = data.get('age', None) if age is None: print("Age not found") # 使用 setdefault ...
default_factory()函数用于为定义的类的属性提供默认值,一般情况下,default_factory的值是函数返回的值。 Python 中的 defaultdict.get(key, default value) 代码示例: fromcollectionsimportdefaultdict# the default value for the undefined keydefdef_val():return"Not present"dic = defaultdict(def_val) dic["x...
1,字典的 get() 方法 get() 方法帮助文档 get(key,default=None,/)methodofbuiltins.dictinstanceReturnthevalueforkeyifkeyisinthedictionary,elsedefault. 在get() 的参数中,key 表示键——对此很好理解,要根据键读取“值”,必然要告诉此方法“键”是什么;还有一个关键词参数 default=None ,默认值是 None ,...
a.update([b]) updates (and overwrites) key/value pairs from b从b字典中更新a字典,如果键相同则更新,a中不存在则追加 (9) a.fromkeys(seq[, value]) Creates a new dictionary with keys from seq and values set to value (7) a.values() a copy of a's list of values (3) a.get(k[,...
""" Create a new dictionary with keys from iterable and values set to value. """ pass 翻译:用可迭代对象创建一个新的字典 View Code 4.get def get(self, *args, **kwargs): # real signature unknown """ Return the value for key if key is in the dictionary, else default. """ ...
counts[word] = counts.get(word, 0) + 1 1. 2. 3. 4. 5. 6. 2、dict.setdefault() 方法 setdefault(key[, default]) 1. If key is in the dictionary, return its value. If not, insert key with a value of default and return default. default defaults to None ...
charlie_grade = student_grades.get("Charlie") # .jpg 或 None(如果不存在) # 使用get()避免KeyError default_grade = student_grades.get("David", 75) # 当键不存在时返回默认值2.1.2.2 字典的增删改操作 字典提供了相应的方法来操作键值对: ...
wibble = planet.get('wibble')# Returns Nonewibble = planet['wibble']# Throws KeyError Modify dictionary values You can also modify values inside a dictionary object, by using theupdatemethod. This method accepts a dictionary as a parameter, and updates any...