Several ways to get values from python dictionary

A 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 often used to store key-value pairs of data, such as records in a database.

　　The following are several methods and code demonstrations of Python dictionary values:

　　Method 1: Use square brackets [ ] operator

　　Use the square brackets [ ] operator to get the corresponding value in the dictionary 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

　　Method 2: Use the get() method

　　Use the get() method to get the corresponding value in the dictionary through the key, and return None if the key does not exist.

# 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

　　Method 3: Use the items() method

　　Use the items() method to get all key-value pairs in the dictionary and return a list containing all key-value pairs. Each element in the list is a tuple. The first element of the tuple is the key, and the second element is 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}")

　　Method 4: Use the keys() method

　　Use the keys() method to get all the keys in the dictionary and return a list containing all the 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}")

　　Method 5: Use the values() method

　　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

　　Method 6: Use the in keyword

　　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

　　Method 7: Use the pop() method

　　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"}

　　Method 8: Use the popitem() method

　　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 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"}

# 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 are several methods of Python dictionary values and their code demonstrations.

Several ways to get values from python dictionary

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