collections.Counter付加エラー

Question

と仮定次のように私たちは、コードスニペットを持っている：

from collections import namedtuple, Counter 

Experiment = namedtuple('Experiment', ['day', 'distribution']) 
LabResults = namedtuple('LabResults', ['lab_name', 'experiments_data']) 

lab_results_list_good = [ 
    LabResults(
     'Lab A', 
     [ 
      Experiment('first_day', Counter('abc')), 
      Experiment('second_day', Counter('')) 
     ], 
    ), 
    LabResults(
     'Lab B', 
     [ 
      Experiment('first_day', Counter('')), 
      Experiment('second_day', Counter('a')), 
     ] 
    ) 
] 

lab_results_list_bad = [ 
    LabResults(
     'Lab A', 
     [ 
      Experiment('first_day', Counter('abc')), 
      Experiment('second_day', Counter('def')) 
     ], 
    ), 
    LabResults(
     'Lab B', 
     [ 
      Experiment('first_day', Counter('ghi')), 
     ] 
    ) 
] 


def merge_distributions(lab_results_list): 
    day_to_distribution_report = Counter() 
    for lab_result in lab_results_list: 

     curr_day_to_dist = Counter({exp.day: exp.distribution for exp in lab_result.experiments_data}) 
     day_to_distribution_report += curr_day_to_dist 
    return day_to_distribution_report 

最初のケースが正常に動作し、後者の場合は動作しません：

In [2]: print merge_distributions(lab_results_list_good) 
Counter({'first_day': Counter({'a': 1, 'c': 1, 'b': 1}), 'second_day': Counter({'a': 1})}) 

In [3]: print merge_distributions(lab_results_list_bad) 
--------------------------------------------------------------------------- 
TypeError         Traceback (most recent call last) 
<ipython-input-3-969bd085f2e5> in <module>() 
----> 1 print merge_distributions(lab_results_list_bad) 

<ipython-input-1-0bdc39e8c846> in merge_distributions(lab_results_list) 
    42 
    43   curr_day_to_dist = Counter({exp.day: exp.distribution for exp in lab_result.experiments_data}) 
---> 44   day_to_distribution_report += curr_day_to_dist 
    45  return day_to_distribution_report 

/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/collections.pyc in __add__(self, other) 
    642   result = Counter() 
    643   for elem, count in self.items(): 
--> 644    newcount = count + other[elem] 
    645    if newcount > 0: 
    646     result[elem] = newcount 

TypeError: unsupported operand type(s) for +: 'Counter' and 'int' 

のPython 2では2番目のケースでは機能しません.Python 3では両方が動作しません。

私の質問は、Python 3が両方のケースを実行するのに失敗するため、カウンターのカウンターをマージすることは本当に悪い考えですか？これはCounterオブジェクトのサポート追加としてのバグのようです。

EDIT私はmerge_distribution機能のための速い修正を見つける：

def merge_distributions(lab_results_list): 
    day_range = {exp.day for lab_result in lab_results_list for exp in lab_result.experiments_data} 
    day_to_distribution_report = Counter() 
    for lab_result in lab_results_list: 

     curr_day_to_dist = Counter({exp.day: exp.distribution for exp in lab_result.experiments_data}) 
     map(lambda day: curr_day_to_dist.setdefault(day, Counter()), day_range) 
     day_to_distribution_report += curr_day_to_dist 
    return day_to_distribution_report 

はなぜPythonのソースは、デフォルトではそのようなことをしないのですか？カウンターは、プロパティを持っていない場合は

Answer 1

、それは0、ではない。ここCounter()

>>> from collections import Counter 
>>> c = Counter({ 
...  'a': Counter(), 'b': Counter(), 
... }) 
>>> d = Counter({ 
...  'a': Counter() 
... }) 
>>> c['b'] 
Counter() 
>>> d['b'] 
0 
>>> c['b'] + d['b'] 
Traceback (most recent call last): 
    File "<stdin>", line 1, in <module> 
TypeError: unsupported operand type(s) for +: 'Counter' and 'int' 
>>> 

がDefaultCounter道具であることをデフォルト：

from collections import Counter 


class DefaultCounter(Counter): 

    def __add__(self, other): 
     if not isinstance(other, Counter): 
      if other == 0: 
       other = Counter() 
      else: 
       return NotImplemented 
     result = Counter() 
     for elem, count in self.items(): 
      newcount = count + other[elem] 
      if newcount > 0: 
       result[elem] = newcount 
     for elem, count in other.items(): 
      if elem not in self and count > 0: 
       result[elem] = count 
     return result 

>>> from m import DefaultCounter 
>>> a = DefaultCounter({'a': DefaultCounter(), 'b': DefaultCounter()}) 
>>> b = DefaultCounter({'a': DefaultCounter()}) 
>>> 
>>> a + b 
Counter({'a': Counter(), 'b': Counter()}) 
# not raise anymore. ^_^