Python-格式化字符串

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我有输入文件：

sun vehicle
one number
two number
reduce command
one speed
five speed
zero speed
speed command
kmh command

我使用以下代码：

from collections import OrderedDict
output = OrderedDict()
with open('final') as in_file:
for line in in_file:    
columns = line.split(' ')
if len(columns) >= 2:
    word,tag = line.strip().split()
    if output.has_key(tag) == False:
        output[tag] = [];
    output[tag].append(word)
else:
    print ""
    for k, v in output.items():
        print '<{}> {} </{}>'.format(k, ' '.join(v), k)
    output = OrderedDict()

我得到的输出为：

<vehicle> sun </vehicle>
<number> one two </number>
<command> reduce speed kmh </command>
<speed> one five zero </speed>

但是我的预期输出应该是：

<vehicle> sun </vehicle>
<number> one two </number>
<command> reduce 
<speed> one five zero </speed>
speed kmh </command>

有人可以帮我解决这个问题吗？

解决方法:

为了递归地解析输入文件,我将创建一个表示标签的类.每个标签可以有其子级.每个子代首先是一个通过tag.children.append(“ value”)手动添加或通过调用tag.add_value(tag.name,“ value”)添加的字符串.

class Tag:
    def __init__(self, name, parent=None):
        self.name = name
        self.children = []
        self.has_root = True
        self.parent = parent

    def __str__(self):
        """ compose string for this tag (recursivly) """
        if not self.children:
            return self.name
        children_str = ' '.join([str(child) for child in self.children])
        if not self.parent:
            return children_str
        return '<%s>%s</%s>' % (self.name, children_str, self.name)

    @classmethod
    def from_file(cls, file):
        """ create root tag from file """
        obj = cls('root')
        columns = []
        with open(file) as in_file:
            for line in in_file:
                value, tag = line.strip().split(' ')
                obj.add_tag(tag, value)
        return obj

    def search_tag(self, tag):
        """ search for a tag in the children """
        if self.name == tag:
            return self
        for i, c in enumerate(self.children):
            if isinstance(c, Tag) and c.name == tag:
                return c
            elif isinstance(c, str):
                if c.strip() == tag.strip():
                    self.children[i] = Tag(tag, self)
                    return self.children[i]
            else:
                result = c.search_tag(tag)
                if result:
                    return result

    def add_tag(self, tag, value):
         """
         add a value, tag pair to the children

         Firstly this searches if the value is an child. If this is the
         case it moves the children to the new location

         Afterwards it searches the tag in the children. When found
         the value is added to this tag. If not a new tag object 
         is created and added to this Tag. The flag has_root
         is set to False so the element can be moved later.
         """
         value_tag = self.search_tag(value)
         if value_tag and not value_tag.has_root:
             print("Found value: %s" % value)
             if value_tag.parent:
                 i = value_tag.parent.children.index(value_tag)
                 value = value_tag.parent.children.pop(i)
                 value.has_root = True
             else:
                 print("not %s" % value)

         found = self.search_tag(tag)
         if found:
             found.children.append(value)
         else:
             # no root
             tag_obj = Tag(tag, self)
             self.children.append(tag_obj)
             tag_obj.add_tag(tag, value)
             tag_obj.has_root = False

tags = Tag.from_file('final')
print(tags)

我知道在此示例中,速度标签未添加两次.我希望可以.
很抱歉输入长代码.

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