python–str.lstrip()意外行为

我正在研究scrapy项目,并试图解析我的配置

字符串是attr_title我必须去掉’attr_’并获得标题.我使用了lstrip(‘attr_’),但得到了意想不到的结果.我知道lstrip可以解决这些问题并删除它们,但很难理解它.

In [17]: "attr.title".lstrip('attr.')
Out[17]: 'itle'


PS：我知道有多种提取字符串的解决方案我有兴趣了解这一点.

解决方法:

lstrip遍历结果字符串,直到没有更多的组合与最左边的字符集匹配

下面有一个小插图.

In [1]: "attr.title".lstrip('attr.')
Out[1]: 'itle' # Flow --> "attr." --> "t" --> Next char is 'i' which does not match any combination hence, iteration stops & end result ('itle') is returned
In [2]: "attr.tritle".lstrip('attr.')
Out[2]: 'itle' # "attr." --> "t" --> "r" --> Next char is 'i' which does not match any combination hence, iteration stops & end result ('itle') is returned
In [5]: "attr.itratitle".lstrip('attr.')
Out[5]: 'itratitle' # "attr." --> Next char is 'i' which does not match any combination hence, iteration stops & end result ('itratitle') is returned