blocks|key|988672|text|在我的Python2.7的PyYaml安装中，我更新了__init__.py、constructor.py和loader.py。现在支持load命令的object_pairs_hook选项。我所做的更改的差异如下所示。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|988673|__init__.py

$+diff+__init__.py+Original
64c64
<+def+load(stream,+Loader=Loader,+**kwds):
---
>+def+load(stream,+Loader=Loader):
69c69
<+++++loader+=+Loader(stream,+**kwds)
---
>+++++loader+=+Loader(stream)
75c75
<+def+load_all(stream,+Loader=Loader,+**kwds):
---
>+def+load_all(stream,+Loader=Loader):
80c80
<+++++loader+=+Loader(stream,+**kwds)
---
>+++++loader+=+Loader(stream)

constructor.py

$+diff+constructor.py+Original
20,21c20
<+++++def+__init__(self,+object_pairs_hook=dict):
<+++++++++self.object_pairs_hook+=+object_pairs_hook
---
>+++++def+__init__(self):
27,29d25
<+++++def+create_object_hook(self):
<+++++++++return+self.object_pairs_hook()
<
54,55c50,51
<+++++++++self.constructed_objects+=+self.create_object_hook()
<+++++++++self.recursive_objects+=+self.create_object_hook()
---
>+++++++++self.constructed_objects+=+{}
>+++++++++self.recursive_objects+=+{}
129c125
<+++++++++mapping+=+self.create_object_hook()
---
>+++++++++mapping+=+{}
400c396
<+++++++++data+=+self.create_object_hook()
---
>+++++++++data+=+{}
595c591
<+++++++++++++dictitems+=+self.create_object_hook()
---
>+++++++++++++dictitems+=+{}
602c598
<+++++++++++++dictitems+=+value.get('dictitems',+self.create_object_hook())
---
>+++++++++++++dictitems+=+value.get('dictitems',+{})

loader.py

$+diff+loader.py+Original
13c13
<+++++def+__init__(self,+stream,+**constructKwds):
---
>+++++def+__init__(self,+stream):
18c18
<+++++++++BaseConstructor.__init__(self,+**constructKwds)
---
>+++++++++BaseConstructor.__init__(self)
23c23
<+++++def+__init__(self,+stream,+**constructKwds):
---
>+++++def+__init__(self,+stream):
28c28
<+++++++++SafeConstructor.__init__(self,+**constructKwds)
---
>+++++++++SafeConstructor.__init__(self)
33c33
<+++++def+__init__(self,+stream,+**constructKwds):
---
>+++++def+__init__(self,+stream):
38c38
<+++++++++Constructor.__init__(self,+**constructKwds)
---
>+++++++++Constructor.__init__(self)|code-block|syntax|javascript|988674|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

On my For PyYaml installation for Python 2.7 I updated __init__.py, constructor.py, and loader.py. Now supports object_pairs_hook option for load commands. Diff of changes I made is below.

<pre><code>__init__.py

$ diff __init__.py Original
64c64
&lt; def load(stream, Loader=Loader, **kwds):
---
&gt; def load(stream, Loader=Loader):
69c69
&lt; loader = Loader(stream, **kwds)
---
&gt; loader = Loader(stream)
75c75
&lt; def load_all(stream, Loader=Loader, **kwds):
---
&gt; def load_all(stream, Loader=Loader):
80c80
&lt; loader = Loader(stream, **kwds)
---
&gt; loader = Loader(stream)

constructor.py

$ diff constructor.py Original
20,21c20
&lt; def __init__(self, object_pairs_hook=dict):
&lt; self.object_pairs_hook = object_pairs_hook
---
&gt; def __init__(self):
27,29d25
&lt; def create_object_hook(self):
&lt; return self.object_pairs_hook()
&lt;
54,55c50,51
&lt; self.constructed_objects = self.create_object_hook()
&lt; self.recursive_objects = self.create_object_hook()
---
&gt; self.constructed_objects = {}
&gt; self.recursive_objects = {}
129c125
&lt; mapping = self.create_object_hook()
---
&gt; mapping = {}
400c396
&lt; data = self.create_object_hook()
---
&gt; data = {}
595c591
&lt; dictitems = self.create_object_hook()
---
&gt; dictitems = {}
602c598
&lt; dictitems = value.get('dictitems', self.create_object_hook())
---
&gt; dictitems = value.get('dictitems', {})

loader.py

$ diff loader.py Original
13c13
&lt; def __init__(self, stream, **constructKwds):
---
&gt; def __init__(self, stream):
18c18
&lt; BaseConstructor.__init__(self, **constructKwds)
---
&gt; BaseConstructor.__init__(self)
23c23
&lt; def __init__(self, stream, **constructKwds):
---
&gt; def __init__(self, stream):
28c28
&lt; SafeConstructor.__init__(self, **constructKwds)
---
&gt; SafeConstructor.__init__(self)
33c33
&lt; def __init__(self, stream, **constructKwds):
---
&gt; def __init__(self, stream):
38c38
&lt; Constructor.__init__(self, **constructKwds)
---
&gt; Constructor.__init__(self)
</code></pre>

blocks|key|988697|text|yaml模块允许您指定自定义“表示者”以将Python对象转换为文本，并指定“构造器”以反转该过程。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|988698|_mapping_tag+=+yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG

def+dict_representer(dumper,+data):
++++return+dumper.represent_dict(data.iteritems())

def+dict_constructor(loader,+node):
++++return+collections.OrderedDict(loader.construct_pairs(node))

yaml.add_representer(collections.OrderedDict,+dict_representer)
yaml.add_constructor(_mapping_tag,+dict_constructor)|code-block|syntax|javascript|988699|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The yaml module allow you to specify custom 'representers' to convert Python objects to text and 'constructors' to reverse the process.

<pre><code>_mapping_tag = yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG

def dict_representer(dumper, data):
 return dumper.represent_dict(data.iteritems())

def dict_constructor(loader, node):
 return collections.OrderedDict(loader.construct_pairs(node))

yaml.add_representer(collections.OrderedDict, dict_representer)
yaml.add_constructor(_mapping_tag, dict_constructor)
</code></pre>

blocks|key|988754|text|2015+(及更高版本)选项：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|988755|ruamel.yaml是PyYAML的一个替代品(免责声明:我是这个包的作者)。保留映射的顺序是在2015年的第一个版本(0.1)中添加的内容之一。它不仅保留了字典的顺序，还保留了注释、主播名称、标签，并支持YAML1.2规范(2009年发布)|offset|length|988756|规范说不能保证排序，但YAML文件中当然有排序，适当的解析器可以保留它，并透明地生成一个保持排序的对象。您只需选择正确的解析器、加载器和转储程序：|988757|import+sys
from+ruamel.yaml+import+YAML

yaml_str+=+"""\
3:+abc
conf:
++++10:+def
++++3:+gij+++++#+h+is+missing
more:
-+what
-+else
"""

yaml+=+YAML()
data+=+yaml.load(yaml_str)
data['conf'][10]+=+'klm'
data['conf'][3]+=+'jig'
yaml.dump(data,+sys.stdout)|code-block|syntax|javascript|988758|将为您提供：|988759|3:+abc
conf:
++10:+klm
++3:+jig+++++++#+h+is+missing
more:
-+what
-+else|988760|data的类型是CommentedMap，它的功能类似于字典，但是它有额外的信息，这些信息会一直保留到被转储(包括保留的注释！)|style|CODE|988761|entityMap|0|LINK|mutability|MUTABLE|url|https://pypi.python.org/pypi/ruamel.yaml^0|0|0|B|0|0|0|0|0|0|0|4|8|C|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@$D|14|E|15|1|16]]|A|$]]|$1|F|3|G|5|6|7|17|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|18|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|19|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|1A|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1B|8|@$D|1C|E|1D|S|T]|$D|1E|E|1F|S|T]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]]]

<h1>2015 (and later) option:</h1>

<a href="https://pypi.python.org/pypi/ruamel.yaml" rel="noreferrer">ruamel.yaml</a> is a drop in replacement for PyYAML (disclaimer: I am the author of that package). Preserving the order of the mappings was one of the things added in the first version (0.1) back in 2015. Not only does it preserve the order of your dictionaries, it will also preserve comments, anchor names, tags and does support the YAML 1.2 specification (released 2009)

The specification says that the ordering is not guaranteed, but of course there is ordering in the YAML file and the appropriate parser can just hold on to that and transparently generate an object that keeps the ordering. You just need to choose the right parser, loader and dumper¹:

<pre><code>import sys
from ruamel.yaml import YAML

yaml_str = """\
3: abc
conf:
 10: def
 3: gij # h is missing
more:
- what
- else
"""

yaml = YAML()
data = yaml.load(yaml_str)
data['conf'][10] = 'klm'
data['conf'][3] = 'jig'
yaml.dump(data, sys.stdout)
</code></pre>

will give you:

<pre><code>3: abc
conf:
 10: klm
 3: jig # h is missing
more:
- what
- else
</code></pre>

<code>data</code> is of type <code>CommentedMap</code> which functions like a dict, but has extra information that is kept around until being dumped (including the preserved comment!)

blocks|key|773516|text|这里有一个简单的解决方案，它还可以检查映射中重复的顶级键。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|773517|import+yaml
import+re
from+collections+import+OrderedDict

def+yaml_load_od(fname):
++++"load+a+yaml+file+as+an+OrderedDict"
++++#+detects+any+duped+keys+(fail+on+this)+and+preserves+order+of+top+level+keys
++++with+open(fname,+'r')+as+f:
++++++++lines+=+open(fname,+"r").read().splitlines()
++++++++top_keys+=+[]
++++++++duped_keys+=+[]
++++++++for+line+in+lines:
++++++++++++m+=+re.search(r'%5E([A-Za-z0-9_]%2B)+*:',+line)
++++++++++++if+m:
++++++++++++++++if+m.group(1)+in+top_keys:
++++++++++++++++++++duped_keys.append(m.group(1))
++++++++++++++++else:
++++++++++++++++++++top_keys.append(m.group(1))
++++++++if+duped_keys:
++++++++++++raise+Exception('ERROR:+duplicate+keys:+{}'.format(duped_keys))
++++#+2nd+pass+to+set+up+the+OrderedDict
++++with+open(fname,+'r')+as+f:
++++++++d_tmp+=+yaml.load(f)
++++return+OrderedDict([(key,+d_tmp[key])+for+key+in+top_keys])|code-block|syntax|javascript|773518|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

here's a simple solution that also checks for duplicated top level keys in your map.

<pre><code>import yaml
import re
from collections import OrderedDict

def yaml_load_od(fname):
 "load a yaml file as an OrderedDict"
 # detects any duped keys (fail on this) and preserves order of top level keys
 with open(fname, 'r') as f:
 lines = open(fname, "r").read().splitlines()
 top_keys = []
 duped_keys = []
 for line in lines:
 m = re.search(r'^([A-Za-z0-9_]+) *:', line)
 if m:
 if m.group(1) in top_keys:
 duped_keys.append(m.group(1))
 else:
 top_keys.append(m.group(1))
 if duped_keys:
 raise Exception('ERROR: duplicate keys: {}'.format(duped_keys))
 # 2nd pass to set up the OrderedDict
 with open(fname, 'r') as f:
 d_tmp = yaml.load(f)
 return OrderedDict([(key, d_tmp[key]) for key in top_keys])
</code></pre>

I'd like to get <a href="http://pyyaml.org/" rel="noreferrer">PyYAML</a>'s loader to load mappings (and ordered mappings) into the Python 2.7+ <a href="http://docs.python.org/library/collections.html#collections.OrderedDict" rel="noreferrer">OrderedDict</a> type, instead of the vanilla <code>dict</code> and the list of pairs it currently uses.

What's the best way to do that?

In Python, how can you load YAML mappings as OrderedDicts?

Python

我想让Python的加载器将映射(和有序映射)加载到 2.7+ 类型中，而不是普通的dict和它当前使用的对列表中。那么最好的方法是什么呢？

问在Python中，如何将YAML映射加载为OrderedDicts？
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