How can you merge two or more dictionaries?

Question

Python

This is:

collections = [{'href': 'link1', 'wait': 1},
               {'href': 'link1', 'wait': 2},
               {'href': 'link2', 'wait': 1},
               {'href': 'link3', 'wait': 0}]

In it:

collections = [{'href': 'link1', 'wait': 3},
               {'href': 'link2', 'wait': 1},
               {'href': 'link3', 'wait': 0}]

I tried using Counter, but it only works if the key values ​​are numbers. Well, or I did something wrong there :)
Thank you in advance for your help! The decision does not come to mind, well, not at all.

Answer 1

For real dictionary merging
, you need not to merge dictionaries

result = []
for c in collections:
    inced = 0
    for n, collection in enumerate(result):
        if collection["href"] == c["href"]: 
            result[n]["wait"] += c["wait"]
            inced = 1
    if inced == 0: result.append(c)

You can try like this

result = []
for c in collections:
    for n, collection in enumerate(result):
        if collection["href"] == c["href"]: 
            result[n]["wait"] += c["wait"]
            break
    else: result.append(c)

Answer 2

def merge_dicts(*dict_args):
    """
    Given any number of dicts, shallow copy and merge into a new dict,
    precedence goes to key value pairs in latter dicts.
    """
    result = {}
    for dictionary in dict_args:
        result.update(dictionary)
    return result

z = merge_dicts(a, b, c, d, e, f, g)

Answer 3

res = defaultdict(int)
for d in collections:
    res[d['href']] += d['wait']
res = [dict(zip(('href', 'wait'), c)) for c in sorted(res.items())]

Python2, on the third one, maybe something needs to be fixed. Most of the code is engaged in restoring the original structure, I think you can write it easier. I proceeded from the fact that we know in advance the keys of the dictionary and their number.