Question

有没有人知道为什么我不能从这里打印assignment(1, 67).：

False

或在这里

print [e.text if "Born" in r.text() else 'False' for e in r.nextAll("td span .bday")]

一切正常，除了print ['False' if "Born" not in r.text() else e.text for e in r.nextAll("td span .bday")]我没有空括号['False']。

Answer 1

您将获得空括号，因为r.nextAll()返回一个空迭代器。把它分解成简单的东西。例如：

>>> print ['foo' if False else 'bar' for e in []]
[]
>>> print ['foo' if False else 'bar' for e in [2]]
['bar']
>>> print ['foo' if False else 'bar' for e in [2, 3]]
['bar', 'bar']
>>> print ['foo' if not False else 'bar' for e in []]
[]
>>> print ['foo' if not False else 'bar' for e in [2]]
['foo']
>>> print ['foo' if not False else 'bar' for e in [2, 3]]
['foo', 'foo']
>

如果您不相信这一点，请尝试打印list(r.nextAll("td span .bday"))

Answer 2

叶氏！问题出在list(r.nextAll("td span .bday"))，返回空[]。

我解决了这个问题：

lambda r: [e.text for e in r.nextAll("td span .bday")] or ['False']

谢谢！

python list comprehensions - ['False']没有打印

2 个答案: