def merge_dicts(list_of_dicts: list, missval=None):
'''Merges a list of dicts, having common keys into a single dict
with items appended to a list
>>> d1 = {'a' : 1, 'b': 2, 'c': 3}
>>> d2 = {'a':4, 'b':5 }
>>> d3 = {'d': 5}
>>> merge_dicts([d1, d2, d3], 'NA')
{'a': [1, 4, 'NA'], 'b': [2, 5, 'NA'],
'c': [3, 'NA', 'NA'], 'd': ['NA', 'NA', 5]}
'''
all_keys = []
for d in list_of_dicts:
for k in d.keys():
if k not in all_keys:
all_keys.append(k)
merged = {}
for k in all_keys:
for d in list_of_dicts:
try:
merged[k].append(d.get(k, missval))
except KeyError:
merged[k] = [d.get(k)]
return(merged)
函数的文档字符串已经很清楚了。有没有更有效率的方法来做这个,而不需要编写两个for循环?一个用于在所有字典中查找所有键,另一个用于创建合并后的字典?