小编dou*_*alg的帖子

我正在尝试使用任何一个基于libxml的第三方XML解析器,但我不能,因为我认为我有某种类型的libxml2问题

我将其他链接器标志设置为-lxml2

和/ usr/include/libxml2的标题搜索路径

但是当我尝试编译时,我仍然会得到大量未定义的符号.以下错误是尝试编译TouchXML的结果.

Undefined symbols:
  "_xmlDocDumpFormatMemory", referenced from:
      -[CXMLDocument description] in CXMLDocument.o
  "_xmlXPathNewContext", referenced from:
      -[CXMLNode nodesForXPath:error:] in CXMLNode.o
      -[CXMLNode(CXMLNode_NamespaceExtensions) nodesForXPath:namespaceMappings:error:] in CXMLNode_XPathExtensions.o
  "_xmlOutputBufferFlush", referenced from:
      -[CXMLNode XMLStringWithOptions:] in CXMLNode.o
  "_xmlNodeListGetString", referenced from:
      -[CXMLNode stringValue] in CXMLNode.o
  "_xmlFree", referenced from:
      _xmlFree$non_lazy_ptr in CXMLDocument.o
      _xmlFree$non_lazy_ptr in CXMLNode.o
     (maybe you meant: _xmlFree$non_lazy_ptr)
  "_xmlXPathFreeContext", referenced from:
      -[CXMLNode nodesForXPath:error:] in CXMLNode.o
      -[CXMLNode(CXMLNode_NamespaceExtensions) nodesForXPath:namespaceMappings:error:] in CXMLNode_XPathExtensions.o
  "_xmlNodeDumpOutput", referenced from:
      -[CXMLNode XMLStringWithOptions:] in CXMLNode.o
  "_xmlAddChild", referenced from:
      -[CXMLDocument(CXMLDocument_CreationExtensions) addChild:] in CXMLDocument_CreationExtensions.o
      -[CXMLElement(CXMLElement_CreationExtensions) addChild:] in …

假设我有一个元组列表:

fruits = [('apple','red',23),
          ('apple','green',12),
          ('orange','small',12),
          ('orange','large',1)]

如何快速,干净地创建一个新列表,其中包含具有最大数字但对于水果名称唯一的元组.所以理想的结果是:

fruits = [('apple','red',23),
          ('orange','small',12)]

我目前的方法是这样的:

def check_fruit(fruit, a_list):
    for item in a_list:
        if fruit[0] == item[0] and fruit[2] < item[2]:
            return False
    return True
filtered_list = [fruit for fruit in fruits if check_fruit(fruit, fruits)]

如果有更好的方法,请告诉我!谢谢.

我当前的表设置用于“单词”和“短语”之间的多对多关联：

association_table_wp = Table('words_phras', Base.metadata,
                             autoload=True,
                             extend_existing=True)

class Phrase(Base):
    __tablename__ = 'phrases'
    __table_args__ = {'autoload': True}

    def __init__(self, phrase, explanation=None, active=False):
        self.phrase = phrase
        self.explanation = explanation
        self.active = active

class Word(Base):
    __tablename__ = 'words'
    __table_args__ = {'autoload': True}

    def __init__(self, word, word_id=None, active=False):
        self.word = word
        self.word_id = word_id
        self.active = active

Word.phrases = relationship(Phrase,
                            secondary=association_table_wp,
                            backref="words")

现在通常当我想查找一些单词及其短语时我使用：

words = db_session.query(Word).filter(Word.id.in_(word_ids)).\
             options(joinedload(Word.phrases)).\
             all()

这允许我访问words[i].phrases与给定单词相关的短语。

现在，这工作正常，但请注意“active”属性。我想过滤单词的短语，以便只active == True返回带有 的短语。如何才能做到这一点？我尝试了几种连接和 eager_loading 的组合，但没有一个像我希望的那样工作。

非常感谢。