與字典理解刪除嵌套的字典項

Question

我有兩個類型的字典：

blocked = {'-5.00': ['121', '381']} 
all_odds = {'-5.00': '{"121":[1.85,1.85],"381":[2.18,1.73],"16":[2.18,1.61],"18":\ 
      [2.12,1.79]}'} 

我想先檢查.keys()對比（==）是否返回True，在這裏它（既-5.00），那麼我想刪除所有來自all_odds的項目具有列於blocked.values()中的關鍵字。

對於它上面應該導致：

all_odds_final = {'-5.00': '{"16":[2.18,1.61],"18": [2.12,1.79]}'} 

我試圖for loop：

if blocked.keys() == all_odds.keys(): 
    for value in blocked.values(): 
     for v in value: 
      for val in all_odds.values(): 
       val = eval(val) 
       if val.has_key(v): 
        del val[v] 

，你知道是很醜陋再加上它的不正常呢。

Answer 1

首先，使字符串成爲一個字典ast.literal_eval()。 Don't use eval()：

>>> import ast 
>>> all_odds['-5.00'] = ast.literal_eval(all_odds['-5.00']) 

然後你可以使用字典解析：

>>> if blocked.keys() == all_odds.keys(): 
...  print {blocked.keys()[0] : {k:v for k, v in all_odds.values()[0].iteritems() if k not in blocked.values()[0]}} 
... 
{'-5.00': {'18': [2.12, 1.79], '16': [2.18, 1.61]}} 

但是如果你想要的-5.00作爲一個字符串值...

>>> {blocked.keys()[0]:str({k: v for k, v in all_odds.values()[0].iteritems() if k not in blocked.values()[0]})} 
{'-5.00': "{'18': [2.12, 1.79], '16': [2.18, 1.61]}"} 

Answer 2

這裏是你如何能做到約2行相同。我不打算在這裏使用ast或eval，但如果你想使用它，你可以添加。

>>> blocked = {'-5.00': ['121', '381']} 
>>> all_odds = {'-5.00': {'121':[1.85,1.85],'381':[2.18,1.73],'16':[2.18,1.61],'18':\ 
...  [2.12,1.79]}} 
>>> bkeys = [k for k in all_odds.keys() if k in blocked.keys()] 
>>> all_odds_final = {pk: {k:v for k,v in all_odds.get(pk).items() if k not in blocked.get(pk)} for pk in bkeys} 
>>> all_odds_final 
{'-5.00': {'18': [2.12, 1.79], '16': [2.18, 1.61]}} 

Answer 3

這似乎工作：

blocked = {'-5.00': ['121', '381']} 
all_odds = {'-5.00': {"121":[1.85,1.85],"381":[2.18,1.73],"16":[2.18,1.61],"18":\ 
     [2.12,1.79]}} 
all_odds_final = dict(all_odds) 
for key, blocks in blocked.iteritems(): 
    map(all_odds_final[key].pop,blocks,[]) 

如果你不想複製的字典，你可以彈出項目從原來的all_odds詞典：

for key, blocks in blocked.iteritems(): 
    map(all_odds[key].pop,blocks,[]) 

空map函數中的列表是這樣的，pop被None調用，因爲它是第二個參數。沒有它彈出只有一個參數，並會返回一個錯誤，如果該鍵不存在。