num1 = dict1.get('apple') num2 = dict1.get('cucumber') num3 =dict1.get('cement','0') 运行结果为 : 1 34 0 有了前面的代码做铺垫,下面的一段长代码就不难理解了: import sys def countchars(filename): count = {} with open(filename) as info
字典(Dictionary)是一种在Python中用于存储和组织数据的数据结构。元素由键和对应的值组成。其中,键(Key)必须是唯一的,而值(Value)则可以是任意类型的数据。在 Python 中,字典使用大括号{}来表示,键和值之间使用冒号:进行分隔,多个键值对之间使用逗号,分隔。
一是先判断一下 key 是否存在,用 in 操作符: 二是使用dict本身提供的一个 get 方法,在Key不存在的时候,返回None: print d.get('Bart') #59 print d.get('Paul') #None 7、在字典中增添一个新元素的方法: d = { 'Adam': 95, 'Lisa': 85, ...
**返回指定键的值。** 参考:https://www.runoob.com/python/att-dictionary-get.html  vulnerabilities = { 80:"HTTP (Hypertext Transfer Protocol) - Used for unencrypted web traffic", 443:"HTTPS (HTTP Secure) - Used for encrypted web traffic", 22:"SSH (Secure Shell) -...
names=["Hard Disk","Laptop","RAM"]itemDictionary=dict(zip(ItemId,names))print(itemDictionary)#...
前面讲到了,我们可以使用变量来指定不同的数据类型,对网工来说,常用的数据类型的有字符串(String), 整数(Integer), 列表(List), 字典(Dictionary),浮点数(Float),布尔(Boolean)。另外不是很常用的但需要了解的数据类型还包括集合(set), 元组(tuple)以及空值(None),下面一一举例讲解。
>>> dictionary == ordered_dict # If a == b True >>> dictionary == another_ordered_dict # and b == c True >>> ordered_dict == another_ordered_dict # then why isn't c == a ?? False # We all know that a set consists of only unique elements, # let's try making a set ...
For this, we use a for loop to iterate through the found list and assign each dictionary to the user variable. We can enumerate the returned list using the keys function to get all the keys that were used in our dictionary. At this point, we can print the rest of our information ...