python - 从特定值之后的列表中删除所有元素

Question

给定一个列表 l1 = ['apple', 'pear', 'grapes, 'banana']

如何删除 'pear' 之后的所有项目

Answer 1

使用列表切片方法

>>> l1 = ['apple', 'pear', 'grapes', 'banana']
>>> target_ibdex = l1.index('pear')
>>> target_ibdex
1
>>> l1[:target_ibdex+1]
['apple', 'pear']
>>> 

---

当列表中不存在元素时进行异常处理。

>>> l1 = ['apple', 'pear', 'grapes', 'banana']
>>> target_element = "mango"
>>> try:
...     target_index = l1.index(target_element) + 1
... except ValueError, e:
...     target_index = None
... 
>>> l1[:target_index]
['apple', 'pear', 'grapes', 'banana']

当元素出现在列表中

>>> l1 = ['apple', 'pear', 'grapes', 'banana']
>>> target_element = "pear"
>>> try:
...     target_index = l1.index(target_element) + 1
... except ValueError, e:
...     target_index = None
... 
>>> l1[:target_index]
['apple', 'pear']