Python 将列表中的字典键从 unicode 编码为 ascii
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Encode keys of dictionaries inside a list from unicode to ascii
提问by mastodon
I have sample response with friends list from facebook:
我有来自 facebook 的朋友列表的示例回复：
[{u'uid': 513351886, u'name': u'Mohammed Hossein', u'pic_small': u'http://profile.ak.fbcdn.net/hprofile-ak-snc4/hs643.snc3/27383_513351886_4933_t.jpg'},
{u'uid': 516583220, u'name': u'Sim Salabim', u'pic_small': u'http://profile.ak.fbcdn.net/hprofile-ak-snc4/hs348.snc4/41505_516583220_5681339_t.jpg'}]
How I could parse through this list encoding key's of the dictionaries to ascii ? I've tried something like this :
我如何将字典的这个列表编码键解析为 ascii ？我试过这样的事情：
response = simplejson.load(urllib.urlopen(REST_SERVER, data))
for k in response:
for id, stuff in k.items():
id.encode("ascii")
logging.debug("id: %s" % id)
return response
But encoded keys are not saved and as a result I'm still getting unicode values.
但是编码的键没有保存，因此我仍然得到 unicode 值。
采纳答案by Karl Knechtel
First: do you really needto do this? The strings are in Unicode for a reason: you simply can't represent everything in plain ASCII that you can in Unicode. This probably won't be a problem for your dictionary keys 'uid', 'name' and 'pic_small'; but it probably won't be a problem to leave them as Unicode, either. (The 'simplejson' library does not know anything about your data, so it uses Unicode for every string - better safe than sorry.)
第一：你真的需要这样做吗？字符串采用 Unicode 是有原因的：您根本无法用纯 ASCII 表示所有内容，而您可以用 Unicode 表示。这对于您的字典键 'uid'、'name' 和 'pic_small' 来说可能不是问题；但将它们保留为 Unicode 也可能不是问题。（'simplejson' 库对您的数据一无所知，因此它对每个字符串使用 Unicode - 比抱歉更安全。）
Anyway:
反正：
In Python, strings cannot be modified. The .encodemethod does not change the string; it returns a new string that is the encoded version.
在 Python 中，字符串不能被修改。该.encode方法不改变字符串；它返回一个新的字符串，它是编码版本。
What you want to do is produce a new dictionary, which replaces the keys with the encoded keys. We can do this by passing each pair of (encoded key, original value) as *args for the dict constructor.
您想要做的是生成一个新字典，用编码的键替换键。我们可以通过将每对（编码键，原始值）作为 *args 传递给 dict 构造函数来实现。
That looks like:
看起来像：
dict((k.encode('ascii'), v) for (k, v) in original.items())
Similarly, we can use a list comprehension to apply this to every dictionary, and create the new list. (We canmodify the list in-place, but this way is cleaner.)
类似地，我们可以使用列表理解将其应用于每个字典，并创建新列表。（我们可以就地修改列表，但这种方式更简洁。）
response = simplejson.load(urllib.urlopen(REST_SERVER, data))
# We create the list of modified dictionaries, and re-assign 'response' to it:
response = [
dict((k.encode('ascii'), v) for (k, v) in original.items()) # the modified version
for original in response # of each original dictionary.
]
return response
回答by Russell Borogove
Your other responses hint at this but don't come out and say it: dictionary lookup and string comparison in Python transparently convert between Unicode and ASCII:
您的其他回复暗示了这一点，但不要出来说出来：Python 中的字典查找和字符串比较透明地在 Unicode 和 ASCII 之间转换：
>>> x = {u'foo':'bar'} # unicode key, ascii value
>>> x['foo'] # look up by ascii
'bar'
>>> x[u'foo'] # or by unicode
'bar'
>>> x['foo'] == u'bar' # ascii value has a unicode equivalent
True
So for most uses of a dictionary converted from JSON, you don't usually need to worry about the fact that everything's Unicode.
因此，对于从 JSON 转换而来的字典的大多数用途，您通常不需要担心一切都是 Unicode 的事实。
