02-python中列表的增删改查

Posted 2020-10-26 每天进步一点点

增：

append()　　#添加到原有列表的最后

In [1]: names = ["老王","老李","老刘","老张"]

In [2]: names.append("老赵")

In [3]: names
Out[3]: [‘老王‘, ‘老李‘, ‘老刘‘, ‘老张‘, ‘老赵‘]

In [6]: names = ["老王","老李","老刘","老张"]

In [7]: names1 = ["悟空","八戒"]

In [8]: names.append(names1)

In [9]: names
Out[9]: [‘老王‘, ‘老李‘, ‘老刘‘, ‘老张‘, [‘悟空‘, ‘八戒‘]]　　#使用append时，是把names1看做成一个对象，整体打包添加到names对象中。

insert()　　#在某个下标的位置添加内容

In [3]: names
Out[3]: [‘老王‘, ‘老李‘, ‘老刘‘, ‘老张‘, ‘老赵‘]

In [4]: names.insert(0,"小胖")

In [5]: names
Out[5]: [‘小胖‘, ‘老王‘, ‘老李‘, ‘老刘‘, ‘老张‘, ‘老赵‘]

In [6]: names.insert(2,"葫芦娃")

In [7]: names
Out[7]: [‘小胖‘, ‘老王‘, ‘葫芦娃‘, ‘老李‘, ‘老刘‘, ‘老张‘, ‘老赵‘]

extend()　　#把两个列表组合成一个列表

In [1]: name1 = ["老王","老李"]

In [2]: name2 = ["悟空","八戒"]

In [3]: name1.extend(name2)

In [5]: name1
Out[5]: [‘老王‘, ‘老李‘, ‘悟空‘, ‘八戒‘, ‘悟空‘, ‘八戒‘]　　#使用extend的时候，是将name2看作一个序列，将这个序列和name1序列合并，并放在其后面。

删：

pop()　　#删除最后一个元素

In [12]: name1
Out[12]: [‘老王‘, ‘老李‘, ‘悟空‘, ‘八戒‘, ‘悟空‘, ‘八戒‘]

In [13]: name1.pop()
Out[13]: ‘八戒‘

In [14]: name1
Out[14]: [‘老王‘, ‘老李‘, ‘悟空‘, ‘八戒‘, ‘悟空‘]

remove()　　#根据内容删除，只操作一次

In [15]: name1
Out[15]: [‘老王‘, ‘老李‘, ‘悟空‘, ‘八戒‘, ‘悟空‘]

In [16]: name1.remove("八戒")

In [17]: name1
Out[17]: [‘老王‘, ‘老李‘, ‘悟空‘, ‘悟空‘]

del　　#根据下标删除

In [17]: name1
Out[17]: [‘老王‘, ‘老李‘, ‘悟空‘, ‘悟空‘]

In [18]: del name1[0]

In [19]: name1
Out[19]: [‘老李‘, ‘悟空‘, ‘悟空‘]

改：

In [20]: name1
Out[20]: [‘老李‘, ‘悟空‘, ‘悟空‘]

In [21]: name1[2] = "猪八戒"

In [22]: name1
Out[22]: [‘老李‘, ‘悟空‘, ‘猪八戒‘]

查：

in / not in　　#判断是否存在列表里

In [23]: name1
Out[23]: [‘老李‘, ‘悟空‘, ‘猪八戒‘]

In [24]: if "老李" in name1:
   ....:     print("在里面")
   ....: if "小孙" not in name1:
   ....:     print("小孙不在里面")
   ....:     
在里面
小孙不在里面

 

python中获取列表元素的下标

In [1]: names = ["laowang","laoli","laozhang","laozhao"]

In [2]: names.index("laoli")
Out[2]: 1