Python开发之路——Day3

一、列表（list）

1.列表的格式

li = [11,22,"kobe",["lakers","ball",11],(11,22,),{"k1":11,"k2":"kuzma"},True,False]

2.列表可以嵌套任何格式，数字、字符串、列表、元组、字典、布尔值。

3.索引取值

li = [11,22,"kobe",["lakers","ball",11],(11,22,),{"k1":11,"k2":"kuzma"},True,False]
print(li[1])

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4切片取值

li = [11,22,"kobe",["lakers","ball",11],(11,22,),{"k1":11,"k2":"kuzma"},True,False]
print(li[1:-1])

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5.for循环

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
for item in li:
    print(item)

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6.利用索引修改和删除

修改

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
li[2] = "randle"
print(li)

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删除

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
del li[1]
print(li)

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7.利用切片修改和删除

修改

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
li[0:2] = [33,44]
print(li)

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删除

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
del li[0:4]
print(li)

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8.in 操作

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
v ="ball" in li
print(v)

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9.查找

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
v = li[3][2]
print(v)

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10.转换

字符串转列表

s = "hechouzi"
li = list(s)
print(li)

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列表转字符串

a.列表中有数字，要用for循环

li = [11, 22, "kobe", ["lakers", "ball", 11], (11, 22,), {"k1": 11, "k2": "kuzma"}, True, False]
s = ""
for item in li:
    s = s + str(item)
print(type(s),s)

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b.列表中只有字符串

li = ["123","hahah"]
v = "".join(li)
print(v)

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11.方法

（1）append 原来值最后追加

li = [11, False, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
li.append(22)
print(li)

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（2）clear 清空列表

li = [11, False, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
li.clear()
print(li)

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（3）copy （浅拷贝）

li = [11, False, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
v = li.copy()
print(v)

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（4）count 计算元素出现的次数

li = [11, False,0, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
v = li.count(False)
print(v)

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（5）extend 扩展原列表，参数：可迭代对象

li = [11, False,0, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
li.extend([(11,22),"33"])
print(li)

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（6）index 根据值获取当前值的索引位置（左边优先）

li = [11, False,0, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
v = li.index(False)
print(v)

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（7）insert 在指定索引位置插入元素

li = [11, False,0, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
li.insert(2,"randle")
print(li)

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（8）pop（1：指定索引；2：默认删除最后一个）删除某个值，并获取删除的值

li = [11, False,0, "kobe", ["lakers"], (11, 22,), {"k1": 11, "k2": "kuzma"}]
v = li.pop()
print(li,v)

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（9）remove 删除列表中指定的值，左边优先

li = [11,22,33,33,44]
li.remove(33)
print(li)

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（10）reverse 将列表进行翻转

li = [11,22,33,33,44]
li.reverse()
print(li)

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（11）sort 排序

li = [11,22,33,33,44]
li.sort(reverse = True)
print(li)

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二、元组（tuple）

1.元组的写法，一般在最后加，

tu = (11,"hehcouzi",)

2.元组的一级元素不可被修改，不能增加或删除

3.索引取值

tu = (11,"kobe",[22],{"key1":"ball"},)
v = tu [1]
print(v)

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4.切片取值

tu = (11,"kobe",[22],{"key1":"ball"},)
v = tu [1:-1]
print(v)

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5.for 循环

tu = (11, "kobe", [22], {"key1": "ball"},)
for item in tu:
    print(item)

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6.转换

s = "hehcouzi"
v1 = tuple(s)
v2 = list(v1)
print(v1,v2)

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三、字典（dict）

1.字典的基本结构

info = {“k1”:"v1","k2":"v2"}.key：value

2.字典的value可以是任何值

3.字典和列表不可做key值

4.字典是无序的

5.可以通过索引取值，不能切片

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
v = info["k1"]
print(v)

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6.del删除

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
del info["k1"]
print(info)

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7. for 循环，默认输出key值

a.info.items 输出key和value

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
for item in info.items():
    print(item)

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b.info.values 输出value值

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
for item in info.values():
    print(item)

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8.方法

（1）fromkeys 根据序列，创建字典，并赋予统一的值

v = dict.fromkeys(["k1","k2","k3"],"hahah")
print(v)

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（2）get

a.寻找指定key值的value，找不到报错

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
v =info["k1"]
print(v)

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b.寻找指定key值的value，找不到返回指定值，默认为None

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
v =info.get("k111",11111)
print(v)

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3. pop 删除并获取值

a.删除k1,并返回11111

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
v =info.pop("k1",11111)
print(info,v)

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b.随机删除一个key和它对应的value

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
k,v =info.popitem()
print(k,v,info)

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4.setdefault 设置值，已存在不设置并获取当前的value，不存在则设置并获取value

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
v = info.setdefault("k1",123)
print(info,v)

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5. update 更新

两种方法

info = {"k1":11,"k2":"hechouzi","k3":("lakers"),1:22,True:11,}
# info.update({"k1":123,"k2":"hahaha"})
info.update(k1 = "lakers",k3=111,Ture=111)
print(info)

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Python开发之路——Day3

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