【自用】Python列表常用操作

自用】Python列表常用操作"/>

【自用】Python列表常用操作

列表的增加：

list.append(obj) & list.extend(seq)

a=[1,2]
b=[3,4]
a.append(b) #将b列表当成一个元素，加入a列表
print(a)
a.extend(b) #将b列表的每一个元素逐一加入a列表
print(a)

输出结果：

[1, 2, [3, 4]]
[1, 2, [3, 4], 3, 4]

list.insert(index, obj)

a=[1,2,3,4]
a.insert(2,6)  #2是需要插入的索引位置，6是要插入列表中的对象
print(a)

输出结果：

[1, 2, 6, 3, 4]

列表的删除

del Data[i]

song=["whish you were here","on the run","if","echoes"]
del song[2]     #指定位置删除元素
for songname in song:print(songname)

输出结果：

whish you were here
on the run
echoes

list.pop([index=-1])
index ：可选参数，要移除列表元素的索引值，不能超过列表总长度
默认为 index=-1，删除最后一个列表值

song=["whish you were here","on the run","if","echoes"]
song.pop()
for songname in song:print(songname)
print(" ")
song.pop(1)
for songname in song:print(songname)

输出结果：

whish you were here
on the run
ifwhish you were here
if

list.remove(obj)

song=["whish you were here","on the run","if","echoes"]
song.remove("if")   #直接删除指定内容
for songname in song:print(songname)

列表的查看

in & not in

list=["a","b","c","e","d","e"]
findletter=input("请输入要查询的字母：")
if findletter in list:print("找到了")
else:print("没找到")

输出结果：

请输入要查询的字母：b
找到了

list.index(x[, start[, end]])

list=["a","c","b","e","c","e","d","e"]
print("e的索引值为：",list.index("e",0,5))  
#在索引值[0,5)范围内，找到指定元素对应的下标

输出结果：

e的索引值为： 3

list.count(obj)

list=["a","c","b","e","c","e","d","e"]
print("e出现的次数：",list.count("e"))

输出结果：

e出现的次数： 3

列表的排序和反转

list.reverse() & list.sort( key=None, reverse=False)
reverse = True 降序， reverse = False 升序（默认）

list=["a","c","b","e","c","e","d","e"]
list.reverse()
print("列表反转后：",list)
list.sort()
print("升序：",list)
list.sort(reverse=True)
print("降序：",list)

输出的结果：

列表反转后： ['e', 'd', 'e', 'c', 'e', 'b', 'c', 'a']
升序： ['a', 'b', 'c', 'c', 'd', 'e', 'e', 'e']
降序： ['e', 'e', 'e', 'd', 'c', 'c', 'b', 'a']

学习参考：
1.=9&vd_source=84c909a3c400f0b1afb074cb83e7b0c1
2..html