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这篇文章重温Tensorflow上的RNNs的使用最佳实践，特别是在官网上没有得到很好记录的特性。

[Podcast.__init__ 第71集 - 和Radim Řehůřek聊聊Gensim](https://podcastinit.com/radim-rehurek-gensim.html)

The Python standard library is full of underappreciated gems. One of them

allows for simple and elegant function dispatching based on argument types.

Who hasn’t seen it:

TypeError: datetime.datetime(...) is not JSON serializable

While this shouldn’t be a big deal, it is. The `json` module – that inherited

its API from `simplejson` – offers two ways to serialize objects:

has to know about all custom types you want to serialize. Which means you

either write functions like:

def to_serializable(val):

if isinstance(val, datetime):

}

return str(val)

Which is painful since you have to add serialization for all objects in one

place2.

Put simply, you define a default function and then register additional

versions of that functions depending on the type of the first argument:

from datetime import datetime

from functools import singledispatch

"""Used if *val* is an instance of datetime."""

return val.isoformat() + "Z"

Now you can call `to_serializable()` on `datetime` instances too and single

dispatch will pick the correct function:

>>> json.dumps({"msg": "hi", "ts": datetime.now()},

... default=to_serializable)

'{"ts": "2016-08-20T13:08:59.153864Z", "msg": "hi"}'

This gives you the power to put your serializers wherever you want: along with

the classes, in a separate module, or along with JSON-related code? _You_

2. Although as you can see it’s manageable with `attrs`; maybe [you should use `attrs`](https://glyph.twistedmatrix.com/2016/08/attrs.html)! ↩︎

3. Unfortunately the API Pyramid uses is currently [undocumented](https://github.com/zopefoundation/zope.interface/issues/41) after being transplanted from [`zope.component`](https://docs.zope.org/zope.component/). ↩︎

4. I’ve been told the original incentive for adding single dispatch to the standard library was a more elegant reimplementation of [`pprint`](https://docs.python.org/3.5/library/pprint.html) (that never happened). ↩︎

The real world is messy, and so too is its data. So messy, that a [recent

survey](http://visit.crowdflower.com/data-science-report.html) reported data

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