python 内置数据结构list、set、dict、tuple（三）

# len：获取元组的长度
t = (1,2,3,4,5)
len(t)

5

# max，min：最大最小值
print(max(t))
print(min(t))

5

1

# tuple：转化或创建元组
l = (1,2,3,4,5)
t = tuple(l)
print(t)

t = tuple()
print(t)

(1, 2, 3, 4, 5)

()

# count：计算指定数据出现的次数
t = (2,1,2,3,45,1,1,2,)

print(t.count(2))

# index：求指定元素在元组中的索引位置

print(t.index(45))
# 如果需要的查找的数字是多个，则返回第一个

print(t.index(1))

3

4

1

# 两个变量交换值
a = 1
b = 3

print(a)
print(b)
print("*" * 20)
# java程序员会这么写：
c = a
a = b
b = c
print(a)
print(b)

print("*" * 20)
# python写法
a,b = b,a
print(a)
print(b)

1

3

********************

3

1

********************

1

3

# 集合的定义
s = set()
print(type(s))
print(s)

# 此时，大括号内一定要有值，否则定义出的是一个dict
s = {1,2,3,4,5,6,7}
print(type(s))
print(s)

<class 'set'>

set()

<class 'set'>

{1, 2, 3, 4, 5, 6, 7}

# 如果只是用大括号定义，则定义的是一个dict类型
d = {}
print(type(d))
print(d)

<class 'dict'>

{}

# 成员检测
# in，not in
s = {4,5,"i", "love", "you"}
print(s)

if "love" in s:
    print("Yes")
    
if "haha" not in s:
    print("Yes")

{'you', 4, 5, 'love', 'i'}

Yes

Yes

# for 循环
s = {4,5,"i", "love", "you"}

for i in s:
    print(i)

you

4

5

love

i

# 带有元组的集合遍历
s = {(1,2,3,), ("i", "love", "you"), (4,5,6)}

for k,m,n in s:
    print(k, "--", m, "--", n)
    
for k in s:
    print(k)

i -- love -- you

4 -- 5 -- 6

1 -- 2 -- 3

('i', 'love', 'you')

(4, 5, 6)

(1, 2, 3)

# 普通集合内涵
# 以下集合在初始化后自动过滤掉重复元素
s = {23,223,233,2,4,5,6,3,4,1,5,3}
print(s)

# 普通集合内涵
ss = {i for i in s}
print(ss)

{1, 2, 3, 4, 5, 6, 233, 23, 223}

{1, 2, 3, 4, 5, 6, 233, 23, 223}

# 带条件的集合内涵
sss = {i for i in s if i % 2 == 0}
print(sss)

{2, 4, 6}

# 多循环的集合内涵
s1 = {1,2,3,4}
s2 = {"i", "love", "you"}

s = {m*n for m in s2 for n in s1}
print(s)

s = {m*n for m in s2 for n in s1 if n == 2}
print(s)

{'you', 'youyou', 'love', 'lovelovelovelove', 'lovelovelove', 'lovelove', 'iii', 'youyouyouyou', 'ii', 'i', 'iiii', 'youyouyou'}

{'lovelove', 'youyou', 'ii'}

# len，max，min：跟其他基本的函数一致
s = {23,54,72,3,5,3,3,6,1,543}
print(len(s))
print(max(s))
print(min(s))

8

543

1

# set：生成一个集合
l = {1,2,3,4,5,4,3,2,1}
s = set(l)
print(s)

{1, 2, 3, 4, 5}

# add：向集合内添加元素
s = {1}
s.add(3)
print(s)

{1, 3}

# clear
s = {1,2,3,4,5}
print(id(s))
s.clear()
print(id(s))
# 结果表明clear函数是原地清空数据

1370773843528

1370773843528

# copy：拷贝
# remove：移除指定的值，直接改变原有值，如果要删除的值不存在，报错
# discard：移除集合中指定的值跟remove一样，但是如果要删除的话，不报错
s = {23,4,3,5,1,2,3}
s.remove(4)
print(s)
s.discard(1)
print(s)

print("*" * 20)
s.discard(100)
print(s)

s.remove(100)
print(s)

{1, 2, 3, 5, 23}

{2, 3, 5, 23}

********************

{2, 3, 5, 23}

---------------------------------------------------------------------------

KeyError                                  Traceback (most recent call last)

<ipython-input-35-0113522ad176> in <module>

     12 print(s)

     13 

---> 14 s.remove(100)

     15 print(s)

KeyError: 100

# pop 随机移除一个元素
s = {1,2,3,4,5,6,7}
d = s.pop()
print(d)
print(s)

1

{2, 3, 4, 5, 6, 7}

# 集合函数
# intersection：交集
# difference：差集
# union：并集
# issubset：检查一个集合是否为另一个子集
# issuperset：检查一个集合是否为另一个超集
s1 = {1,2,3,4,5,6}
s2 = {5,6,7,8,9}

s_1 = s1.intersection(s2)
print(s_1)

s_2 = s1.difference(s2)
print(s_2)

s_3 = s1.issubset(s2)
print(s_3)

s_4 = s1.issuperset(s2)
print(s_4)

{5, 6}

{1, 2, 3, 4}

False

False

# 集合数学操作
s1 = {1,2,3,4,5,6}
s2 = {5,6,7,8,9}

# 以下不支持
s_1 = s1 - s2
print(s_1)

s_2 = s1 + s2
print(s_2)

{1, 2, 3, 4}

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-45-fac787d752ea> in <module>

      7 print(s_1)

      8 

----> 9 s_2 = s1 + s2

     10 print(s_2)

TypeError: unsupported operand type(s) for +: 'set' and 'set'

# 创建
s = frozenset()
print(type(s))
print(s)

<class 'frozenset'>

frozenset()

# 字典的创建
# 创建空字典1
d = {}
print(type(d))
print(d)

# 创建空字典2
d = dict()
print(d)

# 创建有值的字典，每一组数据用冒号隔开，每一对键值对用逗号隔开
d = {"one":1, "two":2, "three":3}
print(d)

# 用dict创建有内容字典1
d = dict({"one":1, "two":2, "three":3})
print(d)

# 用dict创建有内字典2
# 利用关键参数
d = dict(one=1, two=2, three=3)
print(d)

# 
d = dict( [("one",1), ("two",2), ("three",3)])
print(d)

<class 'dict'>

{}

{}

{'one': 1, 'two': 2, 'three': 3}

{'one': 1, 'two': 2, 'three': 3}

{'one': 1, 'two': 2, 'three': 3}

{'one': 1, 'two': 2, 'three': 3}

# 访问数据
d = {"one":1, "two":2, "three":3}
# 注意访问格式
# 中括号内是键值
print(d["one"])

d["one"] = "eins"
print(d)

# 删除某个操作
# 使用del操作
del d["one"]
print(d)

1

{'one': 'eins', 'two': 2, 'three': 3}

{'two': 2, 'three': 3}

# 成员检测：in，not in
# 成员检测检测时的key内容
d = {"one":1, "two":2, "three":3}

if 2 in d:
    print("value")

if "two" in d:
    print("key")
    
if ("two,2") in d:
    print("kv")

key

# 遍历在python2 和 3 中区别比较大，代码不通用
# 按key值使用for循环
d = {"one":1, "two":2, "three":3}
# 使用for循环，直接按keu值访问
for k in d:
    print(k, d[k])
    
# 上述代码可以改写如下
for k in d.keys():
    print(k, d[k])

# 只访问字典的值
for v in d.values():
    print(v)
    
# 注意以下特殊用法
for k,v in d.items():
    print(k, "--", v)

one 1

two 2

three 3

one 1

two 2

three 3

1

2

3

one -- 1

two -- 2

three -- 3

d = {"one":1, "two":2, "three":3}

# 常规字典生成式
dd = {k:v for k,v in d.items()}
print(dd)

# 加限制条件的字典生成式
dd = {k:v for k,v in d.items() if v % 2 == 0}
print(dd)

{'one': 1, 'two': 2, 'three': 3}

{'two': 2}

# 通用函数：len，max，min，dict
# str(字典)：用于返回字典的字符串格式
d = {"one":1, "two":2, "three":3}
print(str(d))

{'one': 1, 'two': 2, 'three': 3}

# clear：清空字典
# items：返回字典的键值对组成的元组格式

d = {"one":1, "two":2, "three":3}
i = d.items()
print(type(i))
print(i)

<class 'dict_items'>

dict_items([('one', 1), ('two', 2), ('three', 3)])

# keys：返回字典的键组成的一个结构
k = d.keys()
print(type(k))
print(k)

<class 'dict_keys'>

dict_keys(['one', 'two', 'three'])

# values：同理，一个可迭代的结构
v = d.values()
print(type(v))
print(v)

<class 'dict_values'>

dict_values([1, 2, 3])

# get：根据指定键返回相应的值，好处是，可以生成默认值

d = {"one":1, "two":2, "three":3}
print(d.get("oner"))

# get默认值是None，可以设置
print(d.get("one", 100))
print(d.get("one33", 100))

print(d['on333'])

None

1

100

---------------------------------------------------------------------------

KeyError                                  Traceback (most recent call last)

<ipython-input-86-f8c01a58018e> in <module>

      8 print(d.get("one33", 100))

      9 

---> 10 print(d['on333'])

KeyError: 'on333'

# fromkeys：使用指定的序列作为键，使用一个值作为字典的所有键的值
l = ["eins", "zwei", "dree"]
# 注意fromkeys两个参数的类型
# 注意fromkeys的调用主体
d = dict.fromkeys(l, "hahahahaha")
print(d)

{'eins': 'hahahahaha', 'zwei': 'hahahahaha', 'dree': 'hahahahaha'}