Python系统学习第七课

#list(列表）

• del删除

a = [1,2,3,4,5,6]
del a[2]
print(a)

[1, 2, 4, 5, 6]

#使用加号连接两个列表
a = [1,2,3,4]
b = [5,6,7,8]
c = a + b
print(c)

[1, 2, 3, 4, 5, 6, 7, 8]

#使用乘号操作列表
#相当于把n个列表接在一起
a = [1,2,3]
b = a * 3
print(b)

[1, 2, 3, 1, 2, 3, 1, 2, 3]

#成员资格运算
a = [1,2,3,4]
b = 5
c = b in a
print(c)
print(b in a)  #也可以用

False
False

#链表的遍历

• for
• while

a = [1,2,3,4]
for i in a:
    print(i)

1
2
3
4

#一般不用while访问列表
a = [1,2,3,4,5]
length = len(a)
i = 0
while i < length:
    print(a[i])
    i += 1

1
2
3
4
5

#双层列表循环
# a为嵌套列表，或者叫双层列表吧
a = [["one", 1], ["two", 2], ["three", 3]]
for i,j in a:
     print(i, "--", j)

one -- 1
two -- 2
three -- 3

#列表内涵：list content

• 通过list创建一个list b

a = ['1','2','3']
b = [i for i in a]
print(b)

['1', '2', '3']

a = ['1','2','3']
b = [i*10 for i in a]
print(b)

['1111111111', '2222222222', '3333333333']

a = [i for i in range(1,30)]
b = [i for i in a if i%2==0] #过滤掉原来列表中的元素，生成一个新的列表
print(b)

[2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28]

aa = [i for i in range(1, 10)]
print(aa)
bb = [j for j in range(10, 20)]
print(bb)
cc = [m+n for m in aa for n in bb]  # 两个列表的双重循环
print(cc)

[1, 2, 3, 4, 5, 6, 7, 8, 9]
[10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
[11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28]

#关于列表的常用函数

• 求列表长度
• len()
• 求列表的最大值,最小值
• max()，min()

#将其他数据类型转化为列表
a = "i love you!"
print(list(a))
print(a)

['i', ' ', 'l', 'o', 'v', 'e', ' ', 'y', 'o', 'u', '!']
i love you!

#将range产生的数据转化成列表
print(list(range(2,9)))

[2, 3, 4, 5, 6, 7, 8]