[英]How can I add a comment to a YAML file in Python
我正在使用https://pypi.python.org/pypi/ruamel.yaml编写YAML文件
代码是这样的:
import ruamel.yaml
from ruamel.yaml.comments import CommentedSeq
d = {}
for m in ['B1', 'B2', 'B3']:
d2 = {}
for f in ['A1', 'A2', 'A3']:
d2[f] = CommentedSeq(['test', 'test2'])
if f != 'A2':
d2[f].fa.set_flow_style()
d[m] = d2
with open('test.yml', "w") as f:
ruamel.yaml.dump(
d, f, Dumper=ruamel.yaml.RoundTripDumper,
default_flow_style=False, width=50, indent=8)
我只是想在顶部添加评论,如:
# Data for Class A
在YAML数据之前。
在您的with
块中,您可以将任何想要的内容写入文件。 由于您只需要在顶部注释,因此在调用ruamel之前添加对f.write()
调用:
with open('test.yml', "w") as f:
f.write('# Data for Class A\n')
ruamel.yaml.dump(
d, f, Dumper=ruamel.yaml.RoundTripDumper,
default_flow_style=False, width=50, indent=8)
原则上这是可能的,因为你可以对这样的“文件开始”注释进行往返,但是在当前的ruamel.yaml 0.10中并没有得到很好的支持,当然也不是“从头开始”(即没有改变现有的)文件)。 在底部是一个简单的相对不错的解决方案,但我首先想提出一个丑陋的解决方法,并逐步完成如何完成这项工作。
丑陋的 :
执行此操作的丑陋方法是在将YAML数据写入文件之前将注释添加到文件中。 那是插入:
f.write('# Data for Class A\n')
就在ruamel.yaml.dump(...)
之前
一步一步 :
要在数据结构上插入注释,因此上述hack不是必需的,首先需要确保您的d
数据是CommentedMap
类型。 如果通过将注释的YAML加载回c
比较该d
变量与具有注释的变量的差异
import ruamel.yaml
from ruamel.yaml.comments import Comment, CommentedSeq, CommentedMap
d = CommentedMap() # <<<<< most important
for m in ['B1', 'B2', 'B3']:
d2 = {}
for f in ['A1', 'A2', 'A3']:
d2[f] = CommentedSeq(['test', 'test2'])
if f != 'A2':
d2[f].fa.set_flow_style()
d[m] = d2
yaml_str = ruamel.yaml.dump(d, Dumper=ruamel.yaml.RoundTripDumper,
default_flow_style=False, width=50, indent=8)
assert not hasattr(d, Comment.attrib) # no attribute on the CommentedMap
comment = 'Data for Class A'
commented_yaml_str = '# ' + comment + '\n' + yaml_str
c = ruamel.yaml.load(commented_yaml_str, Loader=ruamel.yaml.RoundTripLoader)
assert hasattr(c, Comment.attrib) # c has the attribute
print c.ca # and this is what it looks like
print d.ca # accessing comment attribute creates it empty
assert hasattr(d, Comment.attrib) # now the CommentedMap has the attribute
这打印:
Comment(comment=[None, [CommentToken(value=u'# Data for Class A\n')]],
items={})
Comment(comment=None,
items={})
Comment
具有属性comment
,需要将其设置为包含EOL注释(始终只有一个)的2元素列表和前一行注释列表(以CommentTokens
的形式)
要创建CommentToken,您需要一个(假的)StartMark来告诉它启动哪个列:
from ruamel.yaml.error import StreamMark
start_mark = StreamMark(None, None, None, 0, None, None) # column 0
现在您可以创建令牌:
from ruamel.yaml.tokens import CommentToken
ct = CommentToken('# ' + comment + '\n', start_mark, None)
将令牌指定为CommentedMap上前面列表的第一个元素:
d.ca.comment = [None, [ct]]
print d.ca # in case you want to check
给你:
Comment(comment=[None, [CommentToken(value='# Data for Class A\n')]],
items={})
最后:
print ruamel.yaml.dump(d, Dumper=ruamel.yaml.RoundTripDumper)
得到:
# Data for Class A
B1:
A1: [test, test2]
A3: [test, test2]
A2:
- test
- test2
B2:
A1: [test, test2]
A3: [test, test2]
A2:
- test
- test2
B3:
A1: [test, test2]
A3: [test, test2]
A2:
- test
- test2
当然,您不需要创建c
对象,这只是为了说明。
您应该使用的内容 :为了使整个练习更容易一些,您可以忘记细节并在以下方法中对CommentedBase
一次修补:
from ruamel.yaml.comments import CommentedBase
def set_start_comment(self, comment, indent=0):
"""overwrites any preceding comment lines on an object
expects comment to be without `#` and possible have mutlple lines
"""
from ruamel.yaml.error import StreamMark
from ruamel.yaml.tokens import CommentToken
if self.ca.comment is None:
pre_comments = []
self.ca.comment = [None, pre_comments]
else:
pre_comments = self.ca.comments[1]
if comment[-1] == '\n':
comment = comment[:-1] # strip final newline if there
start_mark = StreamMark(None, None, None, indent, None, None)
for com in comment.split('\n'):
pre_comments.append(CommentToken('# ' + com + '\n', start_mark, None))
if not hasattr(CommentedBase, 'set_start_comment'): # in case it is there
CommentedBase.set_start_comment = set_start_comment
然后就是:
d.set_start_comment('Data for Class A')
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.