相关:Is there any pythonic way to combine two dicts (adding values for keys that appear in both)?
我想合并两个字符串:字符串字典,并连接值。以上帖子建议使用collections.Counter
,但它不处理字符串连接。
>>> from collections import Counter
>>> a = Counter({'foo':'bar', 'baz':'bazbaz'})
>>> b = Counter({'foo':'baz'})
>>> a + b
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/collections.py", line 569, in __add__
TypeError: cannot concatenate 'str' and 'int' objects
(我的猜测是Counter尝试将b['baz']
设置为0。)
我想获得{'foo':'barbaz', 'baz':'bazbaz'}
的结果。连接顺序对我来说无关紧要。什么是干净的Pythonic方法呢?
答案 0 :(得分:14)
字典-理解:
>>> d = {'foo': 'bar', 'baz': 'bazbaz'}
>>> d1 = {'foo': 'baz'}
>>> keys = d.viewkeys() | d1.viewkeys()
>>> {k : d.get(k, '') + d1.get(k, '') for k in keys}
{'foo': 'barbaz', 'baz': 'bazbaz'}
对于Python 2.6及更早版本:
>>> dict((k, d.get(k, '') + d1.get(k, '')) for k in keys)
{'foo': 'barbaz', 'baz': 'bazbaz'}
这适用于任何数量的词组:
def func(*dicts):
keys = set().union(*dicts)
return {k: "".join(dic.get(k, '') for dic in dicts) for k in keys}
...
>>> d = {'foo': 'bar', 'baz': 'bazbaz'}
>>> d1 = {'foo': 'baz','spam': 'eggs'}
>>> d2 = {'foo': 'foofoo', 'spam': 'bar'}
>>> func(d, d1, d2)
{'foo': 'barbazfoofoo', 'baz': 'bazbaz', 'spam': 'eggsbar'}
答案 1 :(得分:0)
可以编写通用帮助程序,例如:
a = {'foo':'bar', 'baz':'bazbaz'}
b = {'foo':'baz'}
def concatd(*dicts):
if not dicts:
return {} # or should this be None or an exception?
fst = dicts[0]
return {k: ''.join(d.get(k, '') for d in dicts) for k in fst}
print concatd(a, b)
# {'foo': 'barbaz', 'baz': 'bazbaz'}
c = {'foo': '**not more foo!**'}
print concatd(a, b, c)
# {'foo': 'barbaz**not more foo!**', 'baz': 'bazbaz'}
答案 2 :(得分:0)
一个人可以使用defaultdict
实现这一目标:
from collections import defaultdict
a = {'foo': 'bar', 'baz': 'bazbaz'}
b = {'foo': 'baz'}
new_dict = defaultdict(str)
for key, value in a.items():
new_dict[key] += value
for key, value in b.items():
new_dict[key] += value
print(new_dict)
# defaultdict(<class 'str'>, {'foo': 'barbaz', 'baz': 'bazbaz'})
print(dict(new_dict))
# {'foo': 'barbaz', 'baz': 'bazbaz'}
如果要加入的字典很多,我们可以使用itertools.chain.from_iterable
:
from collections import defaultdict
from itertools import chain
a = {'foo': 'bar', 'baz': 'bazbaz'}
b = {'foo': 'baz'}
c = {'baz': '123'}
dicts = [a, b, c]
new_dict = defaultdict(str)
for key, value in chain.from_iterable(map(dict.items, dicts)):
new_dict[key] += value
print(dict(new_dict))
# {'foo': 'barbaz', 'baz': 'bazbaz123'}