python ==》列表

Posted 2020-09-29

#定义列表
 l=[1,‘a‘,[3,4]] #l=list([1,‘a‘,[3,4]])

#取值：通过列表的索引取值。
　　print (l[0])
　　print (l[1])
　　print(l[2][0])

循环 while
l=[1,2,3,[4,5]]
count = 0
while count < len(l):
    print(l[count])
    count+=1

循环 for
l=[1,2,3,[4,5]]
for count in range (len(l)):
    print (l[count])

把列表的里元素分别打印出来。方法一：
l=[1,2,3,[4,5]]
for count in range (len(l)):
    if type (l[count])is list:
        for i in range(len(l[count])):
            print (l[count][i])
    else:
        print(l[count])

    ‘ok‘

方法二
l=[1,2,3,[4,5]]
l_size = len(l)  #把列表的长度定义为一个变量
for index in range (l_size):
    value=l[index]
    if type (value)is list:
        for i in range(len(value)):
            print (value[i])
    else:
        print(value)

    ok


切片 读操作
l= [‘ab‘,1,2,‘hello‘]
print(l[1:3])#顾头不顾尾
print (l)

追加
l= [‘ab‘,1,2,‘hello‘]
l.append(‘world‘)
print(l)

列表
l = [1,2,3] # l =list([1,2,3])
print  (type(l))
print (l)

优先掌握:

索引取值
l = [1,2,3,4,5]
print (l[0])

切片
l = [1,2,3,4,5]
print (l[1:4])
print (l)
print (l[1:4:2])  #指定步长
print(l[-2:])
print (l[-3:-1])

追加
hobbies = [‘paly‘,‘eat‘,‘sleep‘,‘study‘]
hobbies.append(‘girls‘)
print (hobbies)

删除
hobbies = [‘play‘,‘eat‘,‘sleep‘,‘study‘]
del hobbies[1]  #利用索引  也是单纯的删除。
hobbies.remove(‘sleep‘)  #单纯的删除，指定元素来删除。
x=hobbies.pop()   #不是单纯的删除，是删除之后有个返回值，我们可以用一个变量来接收返回值。
print (x)
print (hobbies)

队列：先进先出
x = []
x.append(‘first‘)
x.append(‘second‘)
x.append(‘third‘)
print (x)
print(x.pop(0))
print(x.pop(0))
print(x.pop(0))

堆栈
x = []
x.append(‘first‘)
x.append(‘second‘)
x.append(‘third‘)
print (x)
print(x.pop())
print(x.pop())
print(x.pop())

长度
hobbies = [‘eat‘,‘sleep‘,‘plal‘]
print (len(hobbies))

包含
hobbies = [‘play‘,‘eat‘,‘sleep‘]
print (‘study‘ in hobbies)

掌握
hobbies = [‘play‘,‘eat‘,‘sleep‘,‘eat‘]
insert:插入
hobbies.insert(1,‘walk‘)
hobbies.insert(0,[‘walk1‘,‘walk2‘])
print(hobbies)
计数
print(hobbies.count(‘eat‘,))
扩展
hobbies.extend([‘walk‘,‘walk‘,‘walk‘])
print (hobbies)
寻找索引
print (hobbies.index(‘eat‘))

了解
clear 清空
hobbies.clear()
print (hobbies)

copy 复制
hobbies.copy()

reverse  翻转
hobbies.reverse()

sort 排序
hobbies.sort()