CODEWITHSUNDEEP
pythondictionarymerge
day
day

Reputation: 93

Merge two dictionaries in Python with the same keys

I have two dictionaries with exaclty the same keys. The first dictionary is :

 { "key_1" : "AR" ,
   "key_2":"BR" ,
   "key_3" : "CR" }

the second is : 

{ "key_1" : "signinfication of AR" ,
  "key_2":" signinfication of  BR" ,
  "key_3" : " signinfication of  CR" }

and I would like to obtain the dictionary below :

{"key_1" : {"AR" : "signinfication of AR"} ,
 "key_2" : {"BR" : "signinfication of BR"} ,
 "key_3" : {"CR" : "signinfication of CR"}

Thank you for your help !

Upvotes: 3

Views: 2198

Answers (3)

cs95
cs95

Reputation: 402323

This is as simple as a one line dict comprehension.

>>> {k : {d1[k]  : d2[k]} for k in d1.keys() & d2.keys()}
{
    "key_2": {
        "BR": " signinfication of  BR"
    },
    "key_1": {
        "AR": "signinfication of AR"
    },
    "key_3": {
        "CR": " signinfication of  CR"
    }
}

Here, d1 and d2 are your two dictionaries. d1.keys() & d2.keys() will perform an intersection on the dictionary keys to ensure that iteration is done over keys that exist in both the dictionaries. Here, that is 

d1.keys() & d2.keys()
{'key_1', 'key_2', 'key_3'}

This is good to have in the general sense when you cannot guarantee that both dictionaries have the exact same keys.

On python2.7 and older, you'd need a slight modification, because keys() returns a list. Use set.intersection - 

>>> {k : {d1[k]  : d2[k]} for k in set(d1.keys()).intersection(d2.keys())}

If you're working with dicts of lists, then the code above requires a zipping between corresponding lists - 

>>> d1
{
    "key_1": [
        "AR",
        "BR",
        "CR"
    ],
    ...
}    
>>> d2
{
    "key_1": [
        "signfication of AR",
        "signfication of BR",
        "signfication of  CR"
    ],
    ...
}

>>> {k : dict(zip(d1[k], d2[k])) for k in d1.keys() & d2.keys()}
{
    "key_1": {
        "BR": "signfication of BR",
        "CR": "signfication of  CR",
        "AR": "signfication of AR"
    },
    "key_3": {
        "CE": " signfication of CE",
        "AE": "signfication of AE",
        "BE": " signfication of BE"
    },
    "key_2": {
        "BZ": "signfication of BZ",
        "CZ": "signfication of CZ",
        "AZ": "signfication of AZ"
    }
}

Upvotes: 9

Ajax1234
Ajax1234

Reputation: 71451

You can try this:

s = { "key_1" : "AR" ,
 "key_2":"BR" ,
 "key_3" : "CR" }

d = { "key_1" : "signinfication of AR" ,
 "key_2":" signinfication of  BR" ,
 "key_3" : " signinfication of  CR" }
new_d = {a:{b:d[a]} for a, b in s.items()}

Output:

{'key_1': {'AR': 'signinfication of AR'}, 'key_3': {'CR': ' signinfication of  CR'}, 'key_2': {'BR': ' signinfication of  BR'}}

Upvotes: 1

RoadRunner
RoadRunner

Reputation: 26315

You could also zip() together the dictionaries items(), and merge them together:

d1 = {"key_1" : "AR",
      "key_2":"BR",
      "key_3" : "CR"}

d2 = {"key_1" : "signinfication of AR",
      "key_2":" signinfication of  BR",
      "key_3" : " signinfication of  CR"}

# make sure both lists have same ordered keys
l1 = sorted(d1.items())
l2 = sorted(d2.items())

d = {k1 : {v1:v2} for (k1, v1), (_, v2) in zip(l1, l2)}

print(d)

Which outputs:

{'key_1': {'AR': 'signinfication of AR'}, 
 'key_2': {'BR': ' signinfication of  BR'}, 
 'key_3': {'CR': ' signinfication of  CR'}}

EDIT:

As @cᴏʟᴅsᴘᴇᴇᴅ recommended, you can call sorted on the lists before zipping them, which ensures that both dictionaries have the same order: key_1, key_2, key_3. You could also do a preliminary check of the keys, such as checking their intersection, to ensure that both dictionaries have the same keys.

Upvotes: 2

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