Python字典的创建
方法一:
- >>> blank_dict = {}
- >>> product_dict = {'MAC':8000,'Iphone':5000, 'ipad':4000, 'mp3': 300}
- >>> product_dict
- {'ipad': 4000, 'MAC': 8000, 'Iphone': 5000, 'mp3': 300}
- >>> blank_dict,product_dict
- ({}, {'ipad': 4000, 'MAC': 8000, 'Iphone': 5000, 'mp3': 300})
方法二:
从Python 2.2版本开始
- >>> fdict = dict((['www','www.linuxeye.com'],['blog','linuxeye.com']))
- >>> fdict
- {'blog': 'linuxeye.com', 'www': 'www.linuxeye.com'}
方法三:
从Python 2.3版本开始, 可以用一个很方便的内建方法fromkeys() 来创建一个"默认"字典, 字典中元素具有相同的值 (如果没有给出, 默认为None):
- >>> fk_dict = {}.fromkeys(('a','b'),'LinuxEye')
- >>> fk_dict
- {'a': 'LinuxEye', 'b': 'LinuxEye'}
- >>> fk2_dict = {}.fromkeys(('yeho','python'))
- >>> fk2_dict
- {'python': None, 'yeho': None}
- >>> fk3_dict = {}.fromkeys('yeho','python')
- >>> fk3_dict
- {'y': 'python', 'h': 'python', 'e': 'python', 'o': 'python'}
Python字典查、增、删、改
- >>> product_dict = {'MAC':8000,'Iphone':5000, 'mp3': 300}
- >>> product_dict['Iphone']
- 5000
- >>> product_dict['ipad'] = 4000 #增
- >>> product_dict
- {'ipad': 4000, 'MAC': 8000, 'Iphone': 5000, 'mp3': 300}
- >>> product_dict.keys() #查看索引
- ['ipad', 'MAC', 'Iphone', 'mp3']
- >>> product_dict.values() #查看值
- [4000, 8000, 5000, 300]
- >>> product_dict.items()
- [('ipad', 4000), ('MAC', 8000), ('Iphone', 5000), ('mp3', 300)]
- >>> for product,price in product_dict.items():
- ... print product,price
- ...
- ipad 4000
- MAC 8000
- Iphone 5000
- mp3 300
- >>> product_dict.has_key('Iphone') #判断key是否存在
- True
- >>> product_dict.has_key('Itouch')
- False
- >>> product_dict.pop('MAC') #删除指定key和value
- 8000
- >>> product_dict
- {'ipad': 4000, 'Iphone': 5000, 'mp3': 300}
- >>> product_dict.popitem() #删除第一个key和value
- ('ipad', 4000)
- >>> product_dict
- {'Iphone': 5000, 'mp3': 300}
- >>> product_dict = {'Iphone': 5000, 'mp3': 300}
- >>> del product_dict['Iphone'] #用del函数删除指定key和value
- >>> product_dict
- {'mp3': 300}
- >>> product_dict['mp3'] = 299 #改
- >>> product_dict
- {'mp3': 299}
- >>> product_dict.clear() #清空字典内容(空字典)
- >>> product_dict
- {}
- >>> del product_dict #删除字典
- >>> product_dict = {'mp3': 300}
- >>> del product_dict #已删除报错
- Traceback (most recent call last):
- File "<stdin>", line 1, in <module>
- NameError: name 'product_dict' is not defined
Tue Oct 15 21:54:26 CST 2013