day04 列表创建、增删改查
- 列表的定义:存储任意类型数据
li = ['123',21,2.4,True,[123,456,'2345']]
- 列表的创建
- 方法一:左边列表名,赋值号右边是中括号,各元素之间逗号隔开
li = ['123',21,2.4,True,[123,456,'2345']]
- 方法二:list(可迭代对象) #将可迭代对线的每一个元素作为列表的每一个元素
l1 = list('abcd1234') #['a', 'b', 'c', 'd', '1', '2', '3', '4']
l2 = list([123,'123,','abc'])
print(l1)
print(l2)
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方法三:列表推导式 后面讲
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列表增加元素
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li.append(variable),将该值追加到列表的末尾,无返回值
l1 = ['太白', '女神', 'xiao','吴老师', '闫龙'] l1.append('xiaozhi') print(l1) #['太白', '女神', 'xiao', '吴老师', '闫龙', 'xiaozhi']
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li.insert(index,'variable'),将该值加到列表指定索引位置,索引超过列表长度时,加到列表末尾
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l1 = ['太白', '女神', 'xiao','吴老师', '闫龙'] l1.insert(0,'坚持') #['坚持', '太白', '女神', 'xiao', '吴老师', '闫龙'] print(l1) l1.insert(6,'xiaozhi') #['坚持', '太白', '女神', 'xiao', '吴老师', '闫龙', 'xiaozhi'] print(l1)
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li.extend(可迭代对象),迭代着追加
l1 = ['太白', '女神', 'xiao','吴老师', '闫龙'] l1.extend('abcd') print(l1) #['太白', '女神', 'xiao', '吴老师', '闫龙', 'a', 'b', 'c', 'd'] l1.extend([123,'abc',[123]]) print(l1) #['太白', '女神', 'xiao', '吴老师', '闫龙', 'a', 'b', 'c', 'd', 123, 'abc', [123]]
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列表元素的删除:li.pop(index),删除指定索引的元素,返回被删除的元素,默认删除最后一个元素
l1 = ['太白', '女神', 'xiao','吴老师', '闫龙']
print(l1.pop(0)) #'太白'
print(l1.pop()) #'闫龙'
li.remove('value'),删除一个指定值元素,重名则删除从左数第一个,无该值则报错
l1 = ['太白','xiaozhi','hello','xiaozhi','world','xiaozhi']
l1.remove('xiaozhi') #['太白', 'hello', 'xiaozhi', 'world', 'xiaozhi']
print(l1)
li.clear(),清空列表,无返回值
l1 = ['太白','xiaozhi','hello','xiaozhi','world','xiaozhi']
print(l1.clear()) #None
print(l1) #[]
del li[index] ,删除指定索引元素
l1 = ['太白','xiaozhi','hello','xiaozhi','world','xiaozhi']
del l1[0] #['xiaozhi', 'hello', 'xiaozhi', 'world', 'xiaozhi']
print(l1)
del li[start_index:end_index:步长] ,按照切片删除
l1 = ['太白','xiaozhi','hello','xiaozhi','world','xiaozhi']
del l1[:3:1]
print(l1)
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列表的改值
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通过索引改值
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通过切片改值
l1 = ['太白','xiaozhi','hello','xiaozhi','world'] l1[1] = '小智' print(l1) #['太白', '小智', 'hello', 'xiaozhi', 'world'] l1[2::1] = 'abcd1234' print(l1) #['太白', '小智', 'a', 'b', 'c', 'd', '1', '2', '3', '4']
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列表的查询
- 通过索引查询
- 通过切片查询
l1 = ['太白','xiaozhi','hello','xiaozhi','world'] print(l1[1]) #xiaozhi print(l1[1:3]) # ['xiaozhi', 'hello']