截取列表前面100行_python列表

# 直接赋值创建列表
L1 = [1, 2, 3, 4, 5]
# list内的数据类型可以不是一个类型
L2 = [1, 2, 3, "jason"]
 
print(L1)
print(L2)
[1, 2, 3, 4, 5]
[1, 2, 3, 'jason']
# 
L3 = list()
print(L3)
print(type(L3))
[]
<class 'list'>

s = "Jason liu"
 
L1 = list(s)
print(type(L1))
print(L1)
<class 'list'>
['J', 'a', 's', 'o', 'n', ' ', 'l', 'i', 'u']
# 列表操作案例
 
L1 = [32, 43, 11, 29, 58]
 
# 使用下标访问
print(L1[0])
#print(L1[15])
 
# 切片操作需要注意取值范围，左包括右不包括
 
L1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
print(L1[1:5])
 
# 切片后生成的是一个全新的列表
# 通过内置函数id可以判断出切片是否生成了全新的列表
 
L2 = L1[0:10]
print(L2)
print(id(L1))
print(id(L2))
 
# 切片下标可以为空
print(L1[:4])
print(L1[2:])
print(L1[:])
 
# 可以控制增长幅度，默认增长幅度为1
print(L1[:5:2])
 
# 下标可以超出范围，超出后不再考虑多余下标内容
print(L1[:100])
 
# 下标增长幅度可以为负数
# 下标为负数，表面顺序是从右往左
# 规定：数组最后一个元素下标是-1
 
#下面例子为空，因为默认是从左向右移动
print(L1[-2:-4])
 
# 如果想利用负数下标打印9，8
print(L1[-2:-4:-1])
 
# 如果想利用负数下标打印8，9
print(L1[-3:-1])
32
[2, 3, 4, 5]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
4370113480
4369266760
[1, 2, 3, 4]
[3, 4, 5, 6, 7, 8, 9, 10]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[1, 3, 5]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[]
[9, 8]
[8, 9]
list1 = [1, 3, 5, 7, 9, 11, 13, 15, 17]
list2 = [5, 8, 10, 12, 15, 20, 22, 30]
 
Set1 = set(list1)
Set2 = set(list2)
Set3 = Set1.union(Set2)
List3 = list(Set3)
List3.sort(reverse=True)
 
for i in List3:
    print(i, end=' ')
30 22 20 17 15 13 12 11 10 9 8 7 5 3 1

#append() 
 
# copy() 复制列表
L1 = [32, 43, 11, 29, 58]
L2 = L1.copy()
print(L2)
 
# count() 计算某个元素在列表中出现的次数
L1 = [32, 43, 11, 29, 58]
print(L1.count(32))
 
# extend() 将一个列表继承另一个列表
b = [1, 2, 3, 4, 5]
b.extend([6, 7, 8])
print(b)
 
# index() 获取值在列表中的索引
b = [1, 2, 3, 4, 5, 2, 4]
print(b.index(2))
print(b.index(3, 2, 5))
 
# insert() 在指定位置前插入元素 
b = [1, 2, 3, 4, 5]
b.insert(2, 9)
print(b)
 
# pop() 根据索引移除列表内一个元素，不给索引默认移除最后一个，返回移除的那个值
b = [1, 2, 3, 4, 5]
print(b.pop())
print(b)
 
# remove() 移除列表中指定的值，返回None
b = [1, 2, 3, 4, 5]
b.remove(3)
print(b)
 
# reverse() 列表翻转
b = [1, 2, 3, 4, 5]
print(id(b))
b.reverse()
print(b)
print(id(b))
 
#sort() 排序
b = [4, 2, 5, 8]
b.sort()
print(b)
b.sort(reverse=True)
print(b)
[32, 43, 11, 29, 58]
1
[1, 2, 3, 4, 5, 6, 7, 8]
1
2
[1, 2, 9, 3, 4, 5]
5
[1, 2, 3, 4]
[1, 2, 4, 5]
4579970184
[5, 4, 3, 2, 1]
4579970184
[2, 4, 5, 8]
[8, 5, 4, 2]

# append()和extend()和insert()
 
a = [1, 2, 3, 4, 5]
a.append([6, 7, 8])
print(a)
 
b = [1, 2, 3, 4, 5]
b.extend([6, 7, 8])
print(b)
 
c = [1, 2, 3, 4, 5]
c.insert(3, 10)
print(c)
[1, 2, 3, 4, 5, [6, 7, 8]]
[1, 2, 3, 4, 5, 6, 7, 8]
[1, 2, 3, 10, 4, 5]
# 假定给出一个列表 member = ["我", "是", "jason"]
# 想要把member变成 member = ["我", 99, "是", 88, "jason", 666]
 
member = ["我", "是", "jason"]
member.insert(1, 99)
print(member)
member.insert(3, 88)
print(member)
member.insert(5, 666)
print(member)
['我', 99, '是', 'jason']
['我', 99, '是', 88, 'jason']
['我', 99, '是', 88, 'jason', 666]
# 请问如何将下边这个列表的"test"修改为"jason“
# ls = [1, 2, ['test'], 3, 5, 8, 13, 18]
ls = [1, 2, ['test'], 3, 5, 8, 13, 18]
ls[2] = ['jason']
print(ls)
[1, 2, ['jason'], 3, 5, 8, 13, 18]
# 将列表推导式还原出来
# ls = [(x, y) for x in range(10) for y in range(10) if x%2 == 0 if y%2!=0]
#ls = [(x, y) for x in range(10) for y in range(10) if x%2 == 0 if y%2!=0]
#print(ls)
ls = list()
for x in range(10):
    for y in range(10):
        if x%2 == 0:
            if y%2 != 0:
                ls.append((x,y))
print(ls)
[(0, 1), (0, 3), (0, 5), (0, 7), (0, 9), (2, 1), (2, 3), (2, 5), (2, 7), (2, 9), (4, 1), (4, 3), (4, 5), (4, 7), (4, 9), (6, 1), (6, 3), (6, 5), (6, 7), (6, 9), (8, 1), (8, 3), (8, 5), (8, 7), (8, 9), (0, 1), (0, 3), (0, 5), (0, 7), (0, 9), (2, 1), (2, 3), (2, 5), (2, 7), (2, 9), (4, 1), (4, 3), (4, 5), (4, 7), (4, 9), (6, 1), (6, 3), (6, 5), (6, 7), (6, 9), (8, 1), (8, 3), (8, 5), (8, 7), (8, 9)]