Python列表的定义及使用

list1 = ["Hello", "一碗周", "你好"]
list2 = [1, 2, 3, 4, 5]
print(list1)  # ['Hello', '一碗周', '你好']
print(list2)  # [1, 2, 3, 4,5]

list1 = list(range(10))
list2 = list("hello")
print(list1)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
print(list2)  # ['h', 'e', 'l', 'l', 'o']

list1 = ["Hello", "一碗周", "你好"]
# 列表的索引
print(list1[1])  # 一碗周
# 列表的切片
print(list1[1:3])  # ['一碗周', '你好']

list1 = ["Hello"]
list2 = ["World"]
list3 = [1, 2, 3, 4, 5]
list4 = list(range(1, 6))

list5 = list1 + list2  # ['Hello', 'World']
print(list5)

list6 = list1 * 3  # ['Hello', 'Hello', 'Hello']
list7 = list3 * 2  # [1, 2, 3, 4, 5, 1, 2, 3, 4, 5]
print(list6)
print(list7)

print("W" in list1)  # False
print("W" in list2)  # False

# 列表的比较运算
# 两个列表比较相等性比的是对应索引位置上的元素是否相等
print(list3 == list4)  # True
list8 = list(range(1, 7))
print(list3 == list8)  # False

list1 = ["H", "e", "l", "l", "o"]
# 方法1
for index in range(len(list1)):
    print(list1[index])
# 方法2
for ch in list1:
    print(ch)

list1 = ["cute", "beautiful", "一碗周"]

# append()在列表尾部添加元素
list1.append("lovely")
print(list1)  # ['cute', 'beautiful', '一碗周', 'lovely']

# insert()在列表指定索引位置插入元素
list1.insert(2, "prefect")
print(list1)  # ['cute', 'beautiful', 'prefect', '一碗周', 'lovely']

# remove()删除指定元素
list1.remove("lovely")
print(list1)  # ['cute', 'beautiful', 'prefect', '一碗周']

# pop()删除指定索引位置的元素
list1.pop(2)
print(list1)  # ['cute', 'beautiful', '一碗周']

# clear()清空列表中的元素
list1.clear()
print(list1)  # []

list1 = ["cute", "beautiful", "甜甜"]

del list1[1]
print(list1) # ['cute', '甜甜']

# 删除整个列表
del list1
print(list1) # NameError: name 'list1' is not defined

list1 = ["beautiful", "cute", "beautiful",
         'prefect', "beautiful", "一碗周", 'lovely']
# 查找"beautiful"第一次出现的位置
print(list1.index("beautiful"))  # 0
# 从第四个元素以后查找"beautiful"最近一次出现的位置
print(list1.index("beautiful", 3))  # 4

# 统计"beautiful"出现的次数
print(list1.count("beautiful"))  # 3

list1 = ["cute", "beautiful", "一碗周"]
list2 = list(range(10))

# 排序
list1.sort()
print(list1)  # ['beautiful', 'cute', '一碗周']

# 反转
list1.reverse()
print(list1)  # ['一碗周', 'cute', 'beautiful']

list2.reverse()
print(list2)  # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

# 前面的操作原来的列表进行修改，如果不让原来的数据被破坏可以使用copy()备份一份
list3 = list2.copy()
list3.sort()
print(list2)  # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
print(list3)  # [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

a = "123"
b = "ABC"
list1 = []
for x in a:
     for y in b:
          list1.append(x + y)
print(list1) # ['1A', '1B', '1C', '2A', '2B', '2C', '3A', '3B', '3C']

a = "123"
b = "ABC"
list1 = [x + y for x in a for y in b]
print(list1) # ['1A', '1B', '1C', '2A', '2B', '2C', '3A', '3B', '3C']

list1 = [["cute", "beautiful", "一碗周"], "cute", "beautiful", "一碗周"]

print(list1[0])  # ['cute', 'beautiful', '一碗周']
print(list1[1])  # cute

# 如果想要查看被嵌套的那个cute则需要使用多个索引值
print(list1[0][0])  # cute