python 列表

Posted 2020-10-14

1.创建列表

创建一个列表，只需要用逗号把数据分隔起来再加上方括号即可，例如

#访问列表中的值，列表中元素按下标为0开始计数

list1=["name","age","stu_num"]

list2=[1,2,3,4,5,6]

print("list1[0]" list1[0])# 按下标找到相应列表的值

print("list2[1:5]"stu_list[1:5])#打印下标从1到5的值但是不包括下标为5的元素

实际输出结果为：list1[0]:name

　　　　　　　　list2[2:5]:[3,4,5]

2.更新列表

list1=["name","age","come from"]

print(list1)#便于列表更新之后作比较

list1[2]="23"

print(list1)

输出结果：["name","23","come from"]

关于list的方法

(1)list.append(obj)#在列表末尾添加一个新对象

list=["a","b","c"]

list.append("welcome")

print(list)

输出结果为:["a","b","c","welcom"]

(2)list.count(obj)统计某个元素在列表中出现的次数

list=["a","b","c"]

print(list.count("a"))

输出结果为：1

(3)list.extend(seq)在列表末尾一次性追加列一个序列中的多个值

list=["a","b","c"]

list1=[1,2,3,4]

list.extend(list1)

print(list)

输出结果：["a","b","c","d",1,2,3,4]

(4)list.index(obj)从列表中找出第一个匹配项的索引位置

list=["a","b","c"]

print(list.index("b"))

输出结果：1

(5)list.insert(index,obj)将对象插入到列表中

list=["a","b","c"]

list.insert(1,"e")

print(list)

输出结果：[a,e,b,c]

(6)list.pop(obj=list[-1])移除列表中的一个元素，默认是最后一个元素，并且返回该元素的值

list=["a","b","c"]

print(list.pop())

print(list.pop(0))

ptint(list)

输出结果:c

　　　　[a,b]

(7)list.remove(obj)移除列表中某个值的第一个匹配项

list=["a","b","c","name","age","city"]

list.remove("name")

print(list)

输出结果：list=["a","b","c","age","city"]

(8)list.reverse()方向列表中的元素

list=["a","b","c","name","age","salary"]

list.reverse()

print(list)

(9)list.sort(func())对原列表进行排序

list=["a","b","c","1name","#age","salary"]
list.sort()
print(list)
输出结果：[‘#age‘, ‘1name‘, ‘a‘, ‘b‘, ‘c‘, ‘salary‘]