在python中删除具有特定子字符串的元素答案

【问题标题】：Deleting elements with specific substring in python在python中删除具有特定子字符串的元素
【发布时间】：2013-06-25 17:48:54
【问题描述】：

我有一个列表，其中包含我使用 Beautiful Soup 从 html 页面中提取的许多元素。在此列表中，我有许多具有相同子字符串的元素，我想提取包含该子字符串的每个元素。

我的列表如下：

[
u'File:Saddam Hussein (107).jpg',
u'Template:Fn (page does not exist)',
u'Template:Fn (page does not exist)',
u'Template:Fn (page does not exist)',
u'Template:Fn (page does not exist)',
u'Template:Fn (page does not exist)',
u'File:AlBakr.jpg',
... (and so on) ...
]

我想删除具有字符串“（页面不存在）”的元素。

有什么想法可以做到这一点吗？

【问题讨论】：

标签： python list

【解决方案1】：

使用列表推导：

>>> lis = [u'File:Saddam Hussein (107).jpg', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'File:AlBakr.jpg', u'Template:Fn (page does not exist)', u'File:Chiracsaddam.jpg', u'File:Donald saddam.jpg', u'Template:Fn (page does not exist)', u'File:SaddamandCuellar.jpg.jpg', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'File:SaddamBaghdadwalkabout.jpg', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'Template:Fn (page does not exist)', u'Kurdish Patriotic Front (page does not exist)', u'File:TrialSaddam.jpg', u'Mohammad Rashdan (page does not exist)', u'Emmanuel Ludot (page does not exist)', u'Marc Henzelin (page does not exist)', u'Adnan Khairallah Tuffah (page does not exist)', u'Nidal al-Hamdani (page does not exist)', u'Ali Hussein (page does not exist)', u'File:SaddamandRana.jpg.jpg', u'Saddam Kamel Majid (page does not exist)', u'Template:Fn (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)', u'Template:Fnb (page does not exist)']

如果要修改原始列表：

>>> lis[:] = [item for item in lis if "(page does not exist)" not in item]

或者创建一个新列表：

new_lis = [item for item in lis if "(page does not exist)" not in item]

【讨论】：

为什么要复制，[:]？我很确定这是不必要的。
@johnthexiii lis[:] 不是副本，请参阅stackoverflow.com/questions/11297774/…
@AshwiniChaudhary，也许更好的问题是为什么要保留原始参考？我并不是暗示这是一件坏事，我只是好奇。
@johnthexiii OP 提到 “想删除”，所以我提供了两种选择。这是唯一的原因。
@johnthexiii：有时更改应该就地进行，例如，os.walk() 允许通过更改 dirs 列表来操作访问的目录。

【解决方案2】：

>>> for i in range(len(l)-1, 0, -1):
...    if l[i].find('(page does not exist)') > -1:
...       del (l[i])
...
>>> l
[u'File:Saddam Hussein (107).jpg']
>>>

【讨论】：

del l[i]- 你不需要括号。另外L 是比l 更好的变量名。
请注意，del 和 pop 是列表的昂贵操作。（pop 比 del 稍快）