When I load a number with e form a JSON dump with YAML, the number is loaded as a string and not a float.
我想这个简单的例子可以解释我的问题.
import json
import yaml
In [1]: import json
In [2]: import yaml
In [3]: All = {'one':1,'low':0.000001}
In [4]: jAll = json.dumps(All)
In [5]: yAll = yaml.safe_load(jAll)
In [6]: yAll
Out[6]: {'low': '1e-06', 'one': 1}
YAML将1e-06作为字符串而不是数字加载？我怎么才能把它修好呢？
The problem lies in the fact that the YAML Resolver is set up to match floats as follows:
Resolver.add_implicit_resolver(
u'tag:yaml.org,2002:float',
re.compile(u'''^(?:[-+]?(?:[0-9][0-9_]*)\\.[0-9_]*(?:[eE][-+][0-9]+)?
|\\.[0-9_]+(?:[eE][-+][0-9]+)?
|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]*
|[-+]?\\.(?:inf|Inf|INF)
|\\.(?:nan|NaN|NAN))$''', re.X),
list(u'-+0123456789.'))
whereas the YAML spec specifies the regex for scientific notation as:
-? [1-9] ( \. [0-9]* [1-9] )? ( e [-+] [1-9] [0-9]* )?
后者使点成为可选的，在隐式解析器中，它不在上述re.compile()个模式中.
The matching of floats can be fixed so it will accept floating point values with an e/E but without decimal dot and with exponents without sign (i.e. + implied):
import yaml
import json
import re
All = {'one':1,'low':0.000001}
jAll = json.dumps(All)
loader = yaml.SafeLoader
loader.add_implicit_resolver(
u'tag:yaml.org,2002:float',
re.compile(u'''^(?:
[-+]?(?:[0-9][0-9_]*)\\.[0-9_]*(?:[eE][-+]?[0-9]+)?
|[-+]?(?:[0-9][0-9_]*)(?:[eE][-+]?[0-9]+)
|\\.[0-9_]+(?:[eE][-+][0-9]+)?
|[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\\.[0-9_]*
|[-+]?\\.(?:inf|Inf|INF)
|\\.(?:nan|NaN|NAN))$''', re.X),
list(u'-+0123456789.'))
data = yaml.load(jAll, Loader=loader)
print 'data', data
results in:
data {'low': 1e-06, 'one': 1}
JSON允许的数字和YAML 1.2规范中的正则表达式之间存在差异(关于数字中所需的点，e是小写).
The PyYAML implementation does match floats partially according to the JSON spec and partially against the regex and fails on numbers that should be valid.
ruamel.yaml(这是我的PyYAML的增强版本)，有这些更新的模式，并且工作正常:
import ruamel.yaml
import json
All = {'one':1,'low':0.000001}
jAll = json.dumps(All)
data = ruamel.yaml.load(jAll)
print 'data', data
with output:
data {'low': 1e-06, 'one': 1}
鲁阿迈尔.yaml还接受数字"1.0e6"，PyYAML也将其视为字符串.