python字典各式各样操作从基础到高级全面示例详解

# 创建字典
my_dict = {'name': 'John', 'age': 25, 'city': 'New York'}
# 访问元素
print(my_dict['name'])  # 输出: John
# 修改元素
my_dict['age'] = 26
# 添加新元素
my_dict['gender'] = 'Male'
# 删除元素
del my_dict['city']

# 字典推导式示例：将列表元素作为键，元素长度作为值
my_list = ['apple', 'banana', 'orange']
length_dict = {fruit: len(fruit) for fruit in my_list}
# 输出: {'apple': 5, 'banana': 6, 'orange': 6}

# 字典合并
dict1 = {'a': 1, 'b': 2}
dict2 = {'b': 3, 'c': 4}
merged_dict = {**dict1, **dict2}
# 输出: {'a': 1, 'b': 3, 'c': 4}
# 字典更新
dict1.update({'b': 3, 'c': 4})
# 输出: {'a': 1, 'b': 3, 'c': 4}

# 嵌套字典
nested_dict = {'person': {'name': 'John', 'age': 25, 'address': {'city': 'New York', 'zip': '10001'}}}

# 字典的键值翻转
flipped_dict = {value: key for key, value in nested_dict['person']['address'].items()}
# 输出: {'New York': 'city', '10001': 'zip'}

# 使用get方法获取默认值
age = my_dict.get('age', 'N/A')  # 如果键不存在，返回默认值 'N/A'
# 使用setdefault方法设置默认值
my_dict.setdefault('gender', 'Unknown')  # 如果键不存在，设置默认值 'Unknown'
# 异常处理
try:
    salary = my_dict['salary']
except KeyError:
    salary = 'Not available'

# 按键排序
sorted_dict_by_key = dict(sorted(my_dict.items()))

# 按值排序
from operator import itemgetter
sorted_dict_by_value = dict(sorted(my_dict.items(), key=itemgetter(1)))

# 字典解析式过滤元素
filtered_dict = {key: value for key, value in my_dict.items() if value > 25}

import json
# 字典序列化为JSON字符串
json_string = json.dumps(my_dict)
# JSON字符串反序列化为字典
restored_dict = json.loads(json_string)

# 数据聚合
data = [
    {'name': 'Alice', 'score': 85},
    {'name': 'Bob', 'score': 92},
    {'name': 'Alice', 'score': 88},
    {'name': 'Bob', 'score': 95},
]
# 使用字典进行数据聚合
score_by_name = {}
for entry in data:
    name = entry['name']
    score = entry['score']
    if name in score_by_name:
        score_by_name[name].append(score)
    else:
        score_by_name[name] = [score]
# 计算每个人的平均分
average_scores = {name: sum(scores) / len(scores) for name, scores in score_by_name.items()}
# 配置管理
default_config = {'debug': False, 'log_level': 'info'}
# 用户配置覆盖默认配置
user_config = {'debug': True, 'log_level': 'debug', 'timeout': 30}
merged_config = {**default_config, **user_config}
# 统计分析
text = "Python is powerful and Python is easy to learn. Python is widely used."
# 统计单词频次
word_frequency = {}
for word in text.split():
    word = word.lower()
    if word in word_frequency:
        word_frequency[word] += 1
    else:
        word_frequency[word] = 1
# 找到频次最高的单词
most_common_word = max(word_frequency, key=word_frequency.get)
# 输出结果
print("Average Scores:", average_scores)
print("Merged Config:", merged_config)
print("Most Common Word:", most_common_word)