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python3速查参考- python基础 4 -> 元组 …

2018-06-17 23:27:53来源：未知阅读 ()

元组

元组：特点就是内容不可变，算只读的列表，可以被查询，不能被修改

a = 2,
print(a)
print(type(a))

b = ('a','b','c')
print(b[1])

运行结果：

(2,)
<class 'tuple'>
b

字典

字典：内部数据打印时是无序的，键值是哈希的，有唯一性

#创建字典
a = {'a':'python','b':'ruby','c':'java'}  #直接创建一个字典
print(a)

#内置字典方法创建：dict
a = dict((('a','b'),))
print(a)

a = dict([['a','b'],])
print(a)

#修改字典
a = {'a': 'b'}
set1 = a.setdefault("c","java")
print(a)
print(set1)

#查询操作
a = {'a':'python','b':'ruby','c':'java'}
print(a.keys())
print(a.values())
print(a.items())
print(a['a'])

#update方法
a = {'a':'python','b':'ruby','c':'java'}
b = {'d':'shell'}
a.update(b)
print(a)
a.update({'a':'javascript'})
print(a)

#删除方法
a = {'a':'python','b':'ruby','c':'java'}
a.clear()
print(a) # 清空字典

a = {'a':'python','b':'ruby','c':'java'}
del a['a']
print(a)

print("********************")
a = {'a':'python','b':'ruby','c':'java'}
b = a.pop('b')
print(a)
print(b)

print("********************")
a = {'a':'python','b':'ruby','c':'java'}
b = a.popitem()
print(a)
print(b)

a = {'a':'python','b':'ruby','c':'java'}
del a  #整个字典被删除

print('其他字典方法')
a = {'first':'python'}
b = dict.fromkeys(['a','b'],['test'])
print(a)
print(b)

print('字典的遍历')
a = {'a':'python','b':'ruby','c':'java'}
for i,j in a.items():
    print(i,j)

for i in a:    #效率比上面的高
    print(i,a[i])

字符串

只列举几个简单的应用

print('join 字符串合并方法')
a = ['python','ruby','java']
b = ''.join(a)
print(b)

c = '*'.join(a)
print(c)


print('字符串常用方法')
a = 'python py'
print(a.count('p'))
print(a.capitalize())

print("format格式化输出")
a = "my favorite book {name} and {name2}"
print(a.format_map({'name':'python','name2':'java'}))
print(a.format(name = 'shell',name2 = 'bash'))
print(a.isdigit())