How to Merge Multiple Dicts with Same Key or Different Key

How to merge dicts, collecting values from matching keys?

assuming all keys are always present in all dicts:

ds = [d1, d2]
d = {}
for k in d1.iterkeys():
    d[k] = tuple(d[k] for d in ds)

Note: In Python 3.x use below code:

ds = [d1, d2]
d = {}
for k in d1.keys():
  d[k] = tuple(d[k] for d in ds)

and if the dic contain numpy arrays:

ds = [d1, d2]
d = {}
for k in d1.keys():
  d[k] = np.concatenate(list(d[k] for d in ds))

Merge two dicts by same key

You almost had it, instead use + to append both lists:

{key: d1[key] + d2[key] for key in d1}

{'a': [2, 4, 5, 6, 8, 10, 12, 15],
 'b': [1, 2, 5, 6, 9, 12, 14, 16],
 'c': [0, 4, 5, 8, 10, 21, 23, 35]}

How to merge dictionaries of dictionaries?

This is actually quite tricky - particularly if you want a useful error message when things are inconsistent, while correctly accepting duplicate but consistent entries (something no other answer here does..)

Assuming you don't have huge numbers of entries, a recursive function is easiest:

def merge(a, b, path=None):
    "merges b into a"
    if path is None: path = []
    for key in b:
        if key in a:
            if isinstance(a[key], dict) and isinstance(b[key], dict):
                merge(a[key], b[key], path + [str(key)])
            elif a[key] == b[key]:
                pass # same leaf value
            else:
                raise Exception('Conflict at %s' % '.'.join(path + [str(key)]))
        else:
            a[key] = b[key]
    return a

# works
print(merge({1:{"a":"A"},2:{"b":"B"}}, {2:{"c":"C"},3:{"d":"D"}}))
# has conflict
merge({1:{"a":"A"},2:{"b":"B"}}, {1:{"a":"A"},2:{"b":"C"}})

note that this mutates a - the contents of b are added to a (which is also returned). If you want to keep a you could call it like merge(dict(a), b).

agf pointed out (below) that you may have more than two dicts, in which case you can use:

reduce(merge, [dict1, dict2, dict3...])

where everything will be added to dict1.

Note: I edited my initial answer to mutate the first argument; that makes the "reduce" easier to explain

PS: In python 3, you will also need from functools import reduce

Merge multiple dicts with same key-value pair to one dict python

This is a perfect scenario to see the power of itertools.groupby
Note that I have assumed haps, state and ads will be present in all dictionaries, and will be similar in repetitions

from itertools import groupby

field_to_be_check =  "state"
merger = ["city", "ads"]
merge_name = ["cities", "my_ads"]

data = [
{'haps': 'hap0', 'state': 'tamil nadu', 'ads': 'ad1', 'city': 'tirunelveli'},
{'haps': 'hap0', 'state': 'tamil nadu', 'ads': 'ad4', 'city': 'nagerkoil'},
{'haps': 'hap0', 'state': 'tamil nadu', 'ads': 'ad1', 'city': 'tuticorin'},
{'haps': 'hap0', 'state': 'tamil nadu', 'ads': 'ad1', 'city': 'madurai'},
{'haps': 'hap0', 'state': 'tamil nadu', 'ads': 'ad1', 'city': 'chennai'},
{'haps': 'hap1', 'state': 'kerala', 'ads': 'ad2', 'city': 'palakad'},
{'haps': 'hap1', 'state': 'kerala', 'ads': 'ad2', 'city': 'guruvayor'},
{'haps': 'hap1', 'state': 'kerala', 'ads': 'ad2', 'city': 'kolikodu'},
{'haps': 'hap1', 'state': 'kerala', 'ads': 'ad2', 'city': 'kottayam'},
{'haps': 'hap1', 'state': 'kerala', 'ads': 'ad2', 'city': 'idukki'},
{'haps': 'hap2', 'state': 'mumbai', 'ads': 'ad3', 'city': 'Akola'},
{'haps': 'hap2', 'state': 'mumbai', 'ads': 'ad3', 'city': 'Washim'},
{'haps': 'hap2', 'state': 'mumbai', 'ads': 'ad3', 'city': 'Jalna'},
{'haps': 'hap2', 'state': 'mumbai', 'ads': 'ad3', 'city': 'Nanded'},
{'haps': 'hap2', 'state': 'mumbai', 'ads': 'ad3', 'city': 'Latur'}
]

#Function to make the merger lists
def process_group(group, merger_item):

    item_set = set()
    item_list = []
    for item in group:
        item_set.add(item[merger_item])

    for item in item_set:
        item_list.append({merger_item: item})

    return item_list

#Group on haps, state and ads
grp = groupby(data,key=lambda x:(x[field_to_be_check]))
result = []

#Iterate through the group and build your result list
for model, group in grp:
    cities_dict = {}

    cities_dict[field_to_be_check] = model

    group_list = list(group)

    #Make the list for merger fields
    for idx, name in enumerate(merger):
        cities_dict[merge_name[idx]] = process_group(group_list, name)

    result.append(cities_dict)

print(result)

The output will look like

[{'state': 'tamil nadu', 
'cities': [{'city': 'nagerkoil'}, {'city': 'tuticorin'}, {'city': 'chennai'}, {'city': 'madurai'}, {'city': 'tirunelveli'}], 
'my_ads': [{'ads': 'ad4'}, {'ads': 'ad1'}]}, 
{'state': 'kerala', 
'cities': [{'city': 'guruvayor'}, {'city': 'idukki'}, {'city': 'kottayam'}, {'city': 'palakad'}, {'city': 'kolikodu'}], 
'my_ads': [{'ads': 'ad2'}]}, 
{'state': 'mumbai', 
'cities': [{'city': 'Jalna'}, {'city': 'Nanded'}, {'city': 'Washim'}, {'city': 'Latur'}, {'city': 'Akola'}], 
'my_ads': [{'ads': 'ad3'}]}]

Combining two dictionaries into one with the same keys?

This is a generic version. This can be used to create a dictionary with values as a list, even if the key is present in only one of them.

dic1 = {'A': 25, 'B': 41, 'C': 32}
dic2 = {'A': 21, 'B': 12, 'C': 62}
result = {}
for key in (dic1.keys() | dic2.keys()):
    if key in dic1: result.setdefault(key, []).append(dic1[key])
    if key in dic2: result.setdefault(key, []).append(dic2[key])

print(result)

Output

{'A': [25, 21], 'C': [32, 62], 'B': [41, 12]}

If you are using Python 2, for loop has to be changed like this:

for key in (dic1.viewkeys() | dic2.keys()):

Combine values of same keys in a list of dicts

bar = {
    k: [d.get(k) for d in foo]
    for k in set().union(*foo)
}

Things to google:

python list comprehension
python dict comprehension
python star
python dict get
python set union

Merge dictionaries with same key from two lists of dicts in python

Here is one of the approach:

a = {
   "name":"harry",
   "properties":[
      {
         "id":"N3",
         "status":"OPEN",
         "type":"energetic"
      },
      {
         "id":"N5",
         "status":"OPEN",
         "type":"hot"
      }
   ]
}
b = {
   "name":"harry",
   "properties":[
      {
         "id":"N3",
         "type":"energetic",
         "language": "english"
      },
      {
         "id":"N6",
         "status":"OPEN",
         "type":"cool"
      }
   ]
}

# Create dic maintaining the index of each id in resp dict
a_ids = {item['id']: index for index,item in enumerate(a['properties'])} #{'N3': 0, 'N5': 1}
b_ids = {item['id']: index for index,item in enumerate(b['properties'])} #{'N3': 0, 'N6': 1}

# Loop through one of the dict created
for id in a_ids.keys():
    # If same ID exists in another dict, update it with the key value
    if id in b_ids:
        b['properties'][b_ids[id]].update(a['properties'][a_ids[id]])
    # If it does not exist, then just append the new dict
    else:
        b['properties'].append(a['properties'][a_ids[id]])
        
        
print (b)

Output:

{'name': 'harry', 'properties': [{'id': 'N3', 'type': 'energetic', 'language': 'english', 'status': 'OPEN'}, {'id': 'N6', 'status': 'OPEN', 'type': 'cool'}, {'id': 'N5', 'status': 'OPEN', 'type': 'hot'}]}

How can I combine dictionaries with the same keys?

big_dict = {}
for k in dicts[0]:
    big_dict[k] = [d[k] for d in dicts]

Or, with a dict comprehension:

{k: [d[k] for d in dicts] for k in dicts[0]}

merge dicts that have the same value for specific key

If lst is list from your question, you can do:

out = {}
for l in lst:
    for d in l:
        out.setdefault(d["tag"], {}).update(d)

print(list(out.values()))

Prints:

[
    {"tag": "#2C00L02RU", "stamina": 233, "health": 200, "fame": 4, "moves": 4},
    {"tag": "#8YG8RJV90", "stamina": 20, "health": 40, "fame": 2, "moves": 0},
    {"tag": "#LQV2JCPR", "stamina": 154, "health": 100, "fame": 1, "moves": 6},
    {"tag": "#9JQLPGLJJ", "stamina": 134, "health": 240, "fame": 3, "moves": 8},
]