Python Dictionary FAQ: Solving Your Troubleshooting

1. How to add key-value pairs to the dictionary?

To add key-value pairs in the dictionary, you can use the following two methods:

# 方法一：使用方括号
my_dict["key"] = "value"

# 方法二：使用 update() 方法
my_dict.update({"key": "value"})

2. How to find a key in a dictionary?

To find a key in a dictionary, you can use the following two methods:

# 方法一：使用 in 运算符
if "key" in my_dict:
print("Key exists")
else:
print("Key does not exist")

# 方法二：使用 get() 方法
value = my_dict.get("key", None)
if value is not None:
print("Key exists")
else:
print("Key does not exist")

3. How to delete key-value pairs in the dictionary?

To delete key-value pairs in the dictionary, you can use the following two methods:

# 方法一：使用 del 关键字
del my_dict["key"]

# 方法二：使用 pop() 方法
value = my_dict.pop("key")

4. How to traverse the dictionary?

Traverse the dictionary, you can use the following two methods:

# 方法一：使用 for 循环
for key, value in my_dict.items():
print(key, value)

# 方法二：使用 keys() 和 values() 方法
for key in my_dict.keys():
print(key)

for value in my_dict.values():
print(value)

5. How to sort the dictionary?

To sort the dictionary, you can use the following two methods:

# 方法一：使用 sorted() 函数
sorted_dict = sorted(my_dict.items(), key=lambda x: x[0])

# 方法二：使用 OrderedDict 类
from collections import OrderedDict
ordered_dict = OrderedDict(sorted(my_dict.items(), key=lambda x: x[0]))

6. How to convert a dictionary to a string?

To convert a dictionary into a string, you can use the following two methods:

# 方法一：使用 str() 函数
string_dict = str(my_dict)

# 方法二：使用 JSON.dumps() 函数
import json
string_dict = json.dumps(my_dict)

7. How to convert string to dictionary?

To convert a string into a dictionary, you can use the following two methods:

# 方法一：使用 eval() 函数
dict_string = "{"key": "value"}"
my_dict = eval(dict_string)

# 方法二：使用 json.loads() 函数
import json
dict_string = "{"key": "value"}"
my_dict = json.loads(dict_string)

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