我需要創建一個 json 文件，給出路徑及其值的字典。我編寫了一些用于添加條目的代碼，看起來它的功能和結果是正確的，但是作為 Python 新手，我想知道如何改進這一點，如果有一個功能相同的功能，模塊中已經存在包含在 python 2.7 中？ def path_to_list(path): if isinstance(path, (str,)): map_list = path.split("/") for i, key in enumerate(map_list): if key.isdigit(): map_list[i] = int(key) else: map_list = path return map_listdef add_to_dictionary(dic, keys, value): for i, key in enumerate(keys[:-1]): if i < len(keys)-1 and isinstance(keys[i+1], int): # Case where current key should be a list, since next key is # is list position if key not in dic.keys(): # Case list not yet exist dic[keys[i]] = [] dic[keys[i]].append({}) dic = dic.setdefault(key, {}) elif not isinstance(dic[key], list): # Case key exist , but not a list # TO DO : check how to handle print "Failed to insert " + str(keys) + ", trying to insert multiple to not multiple " break else: # Case where the list exist dic = dic.setdefault(key, {}) elif i < len(keys)-1 and isinstance(key, int): # Case where current key is instance number in a list try: # If this succeeds instance already exist dic = dic[key] except (IndexError,KeyError): # Case where list exist , but need to add new instances , # as key instance not exist while len(dic)-1 < key: dic.append({}) dic = dic[key] else: # Case where key is not list or instance of list dic = dic.setdefault(key, {}) # Update value dic[keys[-1]] = value一些鍵可能已經存在，然后我只更新值。數字鍵在它可以有多個值之前表示該鍵，我正在數組中的這個地方添加/更新值
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慕尼黑的夜晚無繁華
TA貢獻1864條經驗 獲得超6個贊
這是我使用嵌套字典實現的數據結構：
class Tree(dict):
'''http://stackoverflow.com/questions/635483/what-is-the-best-way-to-implement-nested-dictionaries-in-python'''
def __missing__(d, k):
v = d[k] = type(d)()
return v
def grow(d, path, v):
ps = map(lambda k: int(k) if k.isdigit() else k, path.split('/'))
reduce(lambda d, k: d[k], ps[:-1], d)[ps[-1]] = v
測試這個：
t = Tree()
t.grow('a/0/b/c', 1)
print t
t['a'][2]['b']['c'] = 'string'
print t
t.grow('a/2/b/c', 'new_string')
print t
給出：
{'a': {0: {'b': {'c': 1}}}}
{'a': {0: {'b': {'c': 1}}, 2: {'b': {'c': 'string'}}}}
{'a': {0: {'b': {'c': 1}}, 2: {'b': {'c': 'new_string'}}}}
但是您希望整數索引字典是數組。下面的例程遍歷嵌套的字典，將一些字典變成列表。它會進行一些復制，以免弄亂原始嵌套字典。我只會將它用作 outout 階段的一部分。
import numbers
def keys_all_int(d):
return reduce(lambda r, k: r and isinstance(k, numbers.Integral), d.keys(), True)
def listify(d):
'''
Take a tree of nested dictionaries, and
return a copy of the tree with sparse lists in place of the dictionaries
that had only integers as keys.
'''
if isinstance(d, dict):
d = d.copy()
for k in d:
d[k] = listify(d[k])
if keys_all_int(d):
ds = [{}]*(max(d.keys())+1)
for k in d:
ds[k] = d[k]
return ds
return d
測試這個：
t = Tree()
t.grow('a/0/b/c', 1)
print listify(t)
t['a'][2]['b']['c'] = 'string'
print listify(t)
t.grow('a/2/b/c', 'new_string')
print listify(t)
給出：
{'a': [{'b': {'c': 1}}]}
{'a': [{'b': {'c': 1}}, {}, {'b': {'c': 'string'}}]}
{'a': [{'b': {'c': 1}}, {}, {'b': {'c': 'new_string'}}]}
最后，如果您正在處理 JSON，請使用該json模塊：
import json
print json.dumps(listify(t),
sort_keys=True, indent = 4, separators = (',', ': '))
給出：
{
"a": [
{
"b": {
"c": 1
}
},
{},
{
"b": {
"c": "new_string"
}
}
]
}
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