无损添加或合并Python字典

Question

我正在尝试计算在两台服务器上的日志文件中找到的 IP 地址，然后将字典统计信息合并在一起，而不会丢失元素或计数。我在另一个堆栈溢出问题中找到了部分解决方案，但正如您所看到的，它删除了 '10.10.0.1':7 对。

>>> a = {'192.168.1.21':23,'127.0.0.1':5,'12.12.12.12':5,'55.55.55.55':10}
>>> b = {'192.168.1.21':27,'10.10.0.1':7,'127.0.0.1':1}
>>> c = {}
>>> for elem in a:
...     c[elem] = b.get(elem, 0) + a[elem]
...
>>> print c
{'55.55.55.55': 10, '12.12.12.12': 5, '127.0.0.1': 6, '192.168.1.21': 50}

计数被添加到一起，但是如果字典 a 中不存在该键，则会将其删除。我无法弄清楚最后一点逻辑...也许是 b 中的 elem 的另一个：如果 a.get(elem, 0) 存在：传递 else 将其添加到 c？

Answer 1

在您的代码中，将 c = {} 替换为 c = b.copy()

Answer 2

如果您使用的是 Python 2.7+，请尝试 collections.Counter

否则请尝试以下操作:

a = {'192.168.1.21':23,'127.0.0.1':5,'12.12.12.12':5,'55.55.55.55':10}
b = {'192.168.1.21':27,'10.10.0.1':7,'127.0.0.1':1}
c = {}
for dictionary in (a,b):
    for k,v in dictionary.iteritems():
        c[k] = c.get(k, 0) + v

Answer 3

>>> from collections import Counter
>>> a = {'192.168.1.21':23,'127.0.0.1':5,'12.12.12.12':5,'55.55.55.55':10}
>>> b = {'192.168.1.21':27,'10.10.0.1':7,'127.0.0.1':1}
>>> Counter(a) + Counter(b)
Counter({'192.168.1.21': 50, '55.55.55.55': 10, '10.10.0.1': 7, '127.0.0.1': 6, '12.12.12.12': 5})

Answer 4

怎么样：

c = dict((k, a.get(k, 0) + b.get(k, 0)) for k in set(a.keys() + b.keys()))

Answer 5

如果我明白的话，这应该是对你的问题的一个非常通用的答案。

def merge_sum_dictionaries(*dicts):
    result_dict = {}
    for d in dicts:
        for key, value in d.iteritems():
            result_dict.setdefault(key, 0)
            result_dict[key] += value
    return result_dict



if __name__ == "__main__":
    a = {'192.168.1.21':23,'127.0.0.1':5,'12.12.12.12':5,'55.55.55.55':10}
    b = {'192.168.1.21':27,'10.10.0.1':7,'127.0.0.1':1}

    print merge_sum_dictionaries(a, b)

输出：

{'55.55.55.55': 10, '10.10.0.1': 7, '12.12.12.12': 5, '127.0.0.1': 6, '192.168.1.21': 50}

Answer 6

python 2.6及更高版本的解决方案：

from collections import defaultdict

def merge_count_dicts(*dicts):
    result = defaultdict(int)
    for d in dicts:
        for k, v in d.items():
            result[k] += v
    return result

def test():
    a = {'192.168.1.21':23,'127.0.0.1':5,'12.12.12.12':5,'55.55.55.55':10}
    b = {'192.168.1.21':27,'10.10.0.1':7,'127.0.0.1':1}
    c = merge_count_dicts(a, b)
    print c

if __name__ == '__main_':
    test()