数据结构之字典

在python中，字典是一系列键-值对。每个键都与一个值相关联。键只能是字符串，而与键相关联的值可以是数字、字符串、元组、列表乃至字典。字典中的值可以相同，但键不能有重复

键和值之间用冒号分隔，而键-值对之间用逗号分隔。

1. 创建空字典

# 创建空字典object_dict = dict() # 或者object_dict = {}# 打印字典print (type(object_dict))print (object_dict)

2. 添加键值对

# 创建空字典object_dict = dict() # 或者object_dict = {}# 打印字典print (object_dict)# 添加键值对object_dict['西游记'] = '唐僧'object_dict['水浒传'] = '宋江'object_dict['三国演义'] = '吕布'object_dict['红楼梦'] = '林黛玉'# 打印更新后的字典print (object_dict)

3. 删除键值对

del :删除指定键值对，必须指定字典名和要删除的键

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉'}# 打印字典print (object_dict)# 查找键值对if '西游记' in object_dict.keys():    del object_dict['西游记']# 打印更新后的字典print (object_dict)

4. 修改键值对

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉'}# 打印字典print (object_dict)# 修改键值对if '西游记' in object_dict.keys():    object_dict['西游记'] = '孙悟空'# 打印更新后的字典print (object_dict)

5. 查找键值对

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉'}# 打印字典print (object_dict)# 查找键值对if '西游记' in object_dict.keys():    print ("键：{}  值：{}".format( '西游记', object_dict['西游记']))

6. 遍历字典

6.1 遍历键值对

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉'}# 打印字典print (object_dict)# 遍历键值对for key, value in object_dict.items():    print ("\nKey: " + key)    print ("Value: " + value)

6.2 遍历键

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉'}# 打印字典print (object_dict)# 遍历键值对for key in object_dict.keys():    print ("\nKey: " + key)

6.3 遍历值

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉'}# 打印字典print (object_dict)# 遍历键值对for value in object_dict.values():    print ("\nVlaue: " + value)

7. 集合

set：剔除重复项

# 创建字典object_dict = {'西游记': '唐僧', '水浒传': '宋江', '三国演义': '吕布', '红楼梦': '林黛玉', '白蛇传':'唐僧'}# 打印字典print (object_dict)# 值集合，剔除重复值for value in set(object_dict.values()):    print ("\nVlaue: " + value)

8. 嵌套

未完待续。。。