list的使用

list 查

• count #统计字段出现在列表中的次数

list1=["a","b","c","d"]
print(list1.count("a"))

list1.append("a")
print(list1.count("a"))

---

#1
#2

• index #查看字符所在的下标

list1=["a","b","c","d"]
print(list1)
print(list1.index("b"))

list1.append("b")
print(list1)
print(list1.index("b"))

---

#['a', 'b', 'c', 'd']
#1
#['a', 'b', 'c', 'd', 'b']
#1

list 删除

• remove #删除指定字符

list1=["a","b","c","d"]
print(list1)

list1.remove("a")
print(list1)

---

#['a', 'b', 'c', 'd']
#['b', 'c', 'd']

• pop #删除list中最后一个字段

list1=["a","b","c","d"]
print(list1)

list1.pop()
print(list1)

---

#['a', 'b', 'c', 'd']
#['a', 'b', 'c']

• clear #清空列表

list1=["a","b","c","d"]
print(list1)

list1.clear()
print(list1)

---

#['a', 'b', 'c', 'd']
#[]

list 改

list1=["a","b","c","d","##","12","4","A"]
print(list1)

list1[1]="james.liu"
print(list1)

---

['a', 'b', 'c', 'd', '##', '12', '4', 'A']
['a', 'james.liu', 'c', 'd', '##', '12', '4', 'A']

list 增

• append #追加到列表的最后

list1=["a","b","c","d"]
print(list1)

list1.append("james.liu")
print(list1)

---

#['a', 'b', 'c', 'd']
#['a', 'b', 'c', 'd', 'james.liu']

• insert #插入字符到指定下标

list1=["a","b","c","d"]
print(list1)

list1.insert(3,"zhangsan")
print(list1)

---

#['a', 'b', 'c', 'd']
#['a', 'b', 'c', 'zhangsan', 'd']

• extend #合并两个列表

list1=["a","b","c","d"]
list2=["1","2"]
print(list1)
print(list2)

list1.extend(list2)
print(list1)
print(list2)

---

['a', 'b', 'c', 'd']
['1', '2']
['a', 'b', 'c', 'd', '1', '2']
['1', '2']

list 复制

• copy #浅复制

copy多重列表的时候，列表中的列表拷贝的是一个地址的位置，所以修改的list1[-1][2],list2也会发生改变。

list1=["a","b","c","d"]
print(list1)

list2=list1.copy()
print(list2)

list1=["a","b","c","d",["1","2","3"]]
list2=list1.copy()

list1[2]="james.liu"
list1[-1][2]="james"

print(list1)
print(list2)

---

#['a', 'b', 'c', 'd']
#['a', 'b', 'c', 'd']
#['a', 'b', 'james.liu', 'd', ['1', '2', 'james']]
#['a', 'b', 'c', 'd', ['1', '2', 'james']]

• 通过赋值方式复制

list1=["a","b","c","d",["1","2","3"]]
list2=list1[:]

---

#['a', 'b', 'c', 'd', ['1', '2', '3']]
#['a', 'b', 'c', 'd', ['1', '2', '3']]

reverse 翻转列表

• reverse

list1=["a","b","c","d"]
print(list1)

list1.reverse()
print(list1)

---

#['a', 'b', 'c', 'd']
#['d', 'c', 'b', 'a']

sort #排序

• sort

list1=["a","b","c","d","##","12","4","A"]
print(list1)

list1.sort()
print(list1)

---

#['a', 'b', 'c', 'd', '##', '12', '4', 'A']
#['##', '12', '4', 'A', 'a', 'b', 'c', 'd']

list 切割

list1=["a","b","c","d","##","12","4","A"]

print(list1[:])
print(list1[:3])
print(list1[-2:])
print(list1[2:5])

---

#['a', 'b', 'c', 'd', '##', '12', '4', 'A']
#['a', 'b', 'c']
#['4', 'A']
#['c', 'd', '##']