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Python学习教程:Python列表处理

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Python学习教程:Python列表处理

0、切片操作。同字符串切片操作,这里不多做解释

1、获取列表长度:len

实例:

list=["my","name","is","mark","age",18]print(len(list))list2=[]print(len(list2))

控制台打印结果:

60

2、列表的循环遍历

for循环

list=["my","name","is","mark","age",18]for item in list: print(item)

打印结果:

mynameismarkage18

while循环

list=["my","name","is","mark","age",18]i=0while i<len(list): print(list[i]) i+=1

打印结果:

mynameismarkage18

3、添加元素:append、extend、insert

append:向列表添加元素,添加到尾部

实例:

list=["my","name","is","mark","age",18]print("添加前:",list)list.append("test")print("添加后:",list)

打印结果:

添加前: ['my', 'name', 'is', 'mark', 'age', 18]添加后: ['my', 'name', 'is', 'mark', 'age', 18, 'test']

extend:将另外一个列表的元素逐一添加到指定列表中

实例:

list=["my","name","is","mark","age",18]print("extend前:",list)list2=["A","B"]list.extend(list2)print("extend后:",list)

打印结果:

extend前: ['my', 'name', 'is', 'mark', 'age', 18]extend后: ['my', 'name', 'is', 'mark', 'age', 18, 'A', 'B']

inset(index,objectA):在指定位置index前面插入对象objectA

实例:

list=["my","name","is","mark","age",18]print("insert前:",list)list.insert(3,"test")print("insert后:",list)

打印结果:

insert前: ['my', 'name', 'is', 'mark', 'age', 18]insert后: ['my', 'name', 'is', 'test', 'mark', 'age', 18]

4、修改元素:通过下标修改指定位子元素

实例:

list=["my","name","is","mark","age",18]print("修改前:",list)list[len(list)-1]=19print("修改后:",list)

结果:

修改前: ['my', 'name', 'is', 'mark', 'age', 18]修改后: ['my', 'name', 'is', 'mark', 'age', 19]

5、查找元素:in、not in、index、count

in、not in查找指定元素是否存在,或者不存在

实例:

list=["my","name","is","mark","age",18]print("mark" in list)print("Mark" in list)print("mark" not in list)print("Mark" not in list)

结果:

TrueFalseFalseTrue

index:查找指定元素是否存在,存在返回下标,不存在返回-1

语法:list.index(目标对象[,开始下标,结束下标])

实例:

list=["my","name","is","mark","age",18]print(list.index("name"))print(list.index("name",0,2))print(list.index("name",1,3))

结果:

111

count:返回指定对象在列表中出现的次数

实例:

list=["my","name","is",18,"mark","age",18]print(list.count(18))print(list.count("mark"))print(list.count(19))

结果:

210

6、删除元素:del、pop、remove

del:根据下标删除

pop:删除最后一个元素,相当于弹出栈顶元素,如果指定下标,也可以删除任意位置元素。

remove:根据元素的值进行删除,只删除最先找到的那个

实例:

list=["my","name",18,"is",18,"mark","age",18]print("删除前:",list)del list[1]print("del后:",list)list=["my","name",18,"is",18,"mark","age",18]list.pop()print("pop后:",list)list=["my","name",18,"is",18,"mark","age",18]list.pop(0)print("pop(0)后:",list)list=["my","name",18,"is",18,"mark","age",18]list.remove(18)print("remove后:",list)

结果:

删除前: ['my', 'name', 18, 'is', 18, 'mark', 'age', 18]del后: ['my', 18, 'is', 18, 'mark', 'age', 18]pop后: ['my', 'name', 18, 'is', 18, 'mark', 'age']pop(0)后: ['name', 18, 'is', 18, 'mark', 'age', 18]remove后: ['my', 'name', 'is', 18, 'mark', 'age', 18]

7、排序:sort、reverse、sorted

sort:将数组从小到大排序,参数reverse=True可改成从大到小排序,永久排序

reverse:将数组倒置,永久排序

sorted:效果同sort,只不过是临时排序

实例:

list=[1,3,5,2,7,8,4,0]print("排序前:",list)list.sort()print("sort后:",list)list=[1,3,5,2,7,8,4,0]list.sort(reverse=True)print("sort(reverse=True)后:",list)list=[1,3,5,2,7,8,4,0]list.reverse()print("reverse后:",list)list=[1,3,5,2,7,8,4,0]sorted(list,reverse=True)print("sorted后(临时操作不影响原有列表):",list)list=[1,3,5,2,7,8,4,0]print("sorted后:",sorted(list,reverse=True))

结果:

排序前: [1, 3, 5, 2, 7, 8, 4, 0]sort后: [0, 1, 2, 3, 4, 5, 7, 8]sort(reverse=True)后: [8, 7, 5, 4, 3, 2, 1, 0]reverse后: [0, 4, 8, 7, 2, 5, 3, 1]sorted后(临时操作不影响原有列表): [1, 3, 5, 2, 7, 8, 4, 0]sorted后: [8, 7, 5, 4, 3, 2, 1, 0]

8、列表最大值、最小值、总和:min、max、sum

实例:

list=[1,3,5,2,7,8,4,0]print("列表最小值:%d"%min(list))print("列表最大值:%d"%max(list))print("列表总和:%d"%sum(list))

结果:

列表最小值:0列表最大值:8列表总和:30

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