merger two dict in python like this

Question

I want merge two dict like this:

from:

  a1 = {u'2016-03-11': [u'20:00', u'22:10']}
  a2 = {u'2016-03-11': [u'20:00', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}

to:

  an = {u'2016-03-11': [u'20:00',u'22:10', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}

i need a function merge two dict

Answer 1

from collections import defaultdict


a1 = {u'2016-03-11': [u'20:00', u'22:10']}
a2 = {u'2016-03-11': [u'20:00', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}    

dd = defaultdict(set)
for d in a1, a2:
    for k, v in d.items():
        dd[k] |= set(v)
res = {k: sorted(v) for k, v in dd.items()}

print(res)
# {'2016-03-12': ['20:00', '22:10'], '2016-03-11': ['20:00', '22:10', '23:10']}

Answer 2

a1 = {u'2016-03-11': [u'20:00', u'22:10']}
a2 = {u'2016-03-11': [u'20:00', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}


import copy
an = copy.deepcopy(a1)

for key, value in a2.iteritems():
    if key in an:
        an[key] = list(set(an[key] + a2[key]))
    else:
        an[key] = value

print an

>> {u'2016-03-11': [u'22:10', u'20:00', u'23:10'], u'2016-03-12': [u'20:00', u'22:10']}

Answer 3

Using set, sorted to combine to two list into one and to sort:

>>> a1 = {u'2016-03-11': [u'20:00', u'22:10']}
>>> a2 = {u'2016-03-11': [u'20:00', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}


>>> an = {}
>>> for d in a1, a2:
...     for key in d:
...         an[key] = sorted(set(an.get(key, []) + d[key]))
...         # ^^  Merge two lists (dictionary values) into one, and sort
... 
>>> print an
{u'2016-03-11': [u'20:00', u'22:10', u'23:10'],
 u'2016-03-12': [u'20:00', u'22:10']}

---

UPDATE

alternative version using dictionary comprehension (assuming merging only two dictionaries):

>>> {key: sorted(set(a1.get(key,[]) + a2.get(key,[]))) for key in set(a1)|set(a2)}
{u'2016-03-11': [u'20:00', u'22:10', u'23:10'],
 u'2016-03-12': [u'20:00', u'22:10']}

Answer 4

a1 = {u'2016-03-11': [u'20:00', u'22:10']}
a2 = {u'2016-03-11': [u'20:00', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}


an = a1

for key in a2 :
    if key in an :
        an[key] = list(set(a2[key]+ a2[key]))
        an[key].sort()
    else :
        x = {key : a2[key]}
        an.update(x)

keyList = an.keys()
keyList.sort()
temp = {}
for key in keyList:
    temp.update({key:an[key]})

an = temp 
print an

Answer 5

I derived this option (posted here as an answer):

an = {}
for key in set().union(a1, a2): 
    an[key] = sorted(set().union(a1.get(key, []), a2.get(key, [])))

It builds the sets without list concatenations.

It produces the required result:

>>> a1 = {u'2016-03-11': [u'20:00', u'22:10']}
>>> a2 = {u'2016-03-11': [u'20:00', u'23:10'],u'2016-03-12': [u'20:00', u'22:10']}
>>> an = {}
>>> for key in set().union(a1, a2): 
...     an[key] = sorted(set().union(a1.get(key, []), a2.get(key, [])))
... 
>>> an
{u'2016-03-11': [u'20:00', u'22:10', u'23:10'], u'2016-03-12': [u'20:00', u'22:10']}

Answer 6

It looks awful but it works:

an = {}
for key in set(list(a1.keys()) + list(a2.keys())):
    an[key] = list(set((a1.get(key) or []) + (a2.get(key) or [])))

I am shure there is more clever and pythonic way, though :)