Home > Article > Backend Development > What are the methods to get values from python dictionary?
Python dictionary is a mutable container model that can store any amount of data of any type.
Each element in the dictionary consists of a key and a value, separated by a colon.
Dictionaries are usually used to store key-value pairs of data, such as storing records in a database.
The following are several methods of Python dictionary values and their code demonstrations:
Use square brackets [ ] operator The corresponding value in the dictionary can be obtained by key.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 获取字典中 "name" 键对应的值 value = my_dict["name"] print(value) # 输出:Tom
Use the get() method to get the corresponding value in the dictionary through the key. If the key does not exist, None is returned.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 获取字典中 "name" 键对应的值 value = my_dict.get("name") print(value) # 输出:Tom # 获取字典中 "phone" 键对应的值,由于 "phone" 不存在,返回 None value = my_dict.get("phone") print(value) # 输出:None
Use the items() method to obtain all key-value pairs in the dictionary and return a list containing all key-value pairs. Each item in the list Element is a tuple, the first element of the tuple is the key and the second element is the value.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 获取字典中所有键值对 items = my_dict.items() print(items) # 输出:dict_items([('name', 'Tom'), ('age', 18), ('gender', 'male')]) # 遍历所有键值对 for key, value in items: print(f"{key}: {value}")
Use the keys() method to obtain all keys in the dictionary and return a list containing all keys.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 获取字典中所有键 keys = my_dict.keys() print(keys) # 输出:dict_keys(['name', 'age', 'gender']) # 遍历所有键 for key in keys: value = my_dict[key] print(f"{key}: {value}")
Use the values() method to get all the values in the dictionary and return a list containing all values.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 获取字典中所有值 values = my_dict.values() print(values) # 输出:dict_values(['Tom', 18, 'male']) # 遍历所有值 for value in values: print
Use the in keyword to determine whether a key is in the dictionary. If it is, it returns True, otherwise it returns False.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 判断 "name" 是否在字典中 if "name" in my_dict: print("name is in my_dict") # 输出:name is in my_dict # 判断 "phone" 是否在字典中 if "phone" in my_dict: print("phone is in my_dict") else: print("phone is not in my_dict") # 输出:phone is not in my_dict
Use the pop() method to delete the key-value pair of the specified key in the dictionary and return the corresponding value.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 删除字典中 "age" 键的键值对,并返回对应的值 value = my_dict.pop("age") print(value) # 输出:18 print(my_dict) # 输出:{"name": "Tom", "gender": "male"}
Use the popitem() method to delete any key-value pair in the dictionary and return the corresponding key-value pair. What is returned is a element Group, the first element of the tuple is the key and the second element is the value.
# 定义一个字典 my_dict = {"name": "Tom", "age": 18, "gender": "male"} # 删除字典中的任意一个键值对,并返回对应的键值对 key, value = my_dict.popitem() print(key, value) # 输出:gender male print(my_dict) # 输出:{"name": "Tom", "age": 18}
The above is the detailed content of What are the methods to get values from python dictionary?. For more information, please follow other related articles on the PHP Chinese website!