Update python dictionary (add another value to existing key)

Question

I have simple dictionary with key, value:

d = {\'word\': 1, \'word1\': 2}

I need to add another value (to make a list from values):

Answer 1

you could try the below:

d['word'] = [1, 'something']

d['word1'] = [2, 'something']

call d now

Hope this helps!

Answer 2

Well you can simply use:

d['word'] = [1,'something']

Or in case the 1 needs to be fetched:

d['word'] = [d['word'],'something']

Finally say you want to update a sequence of keys with new values, like:

to_add = {'word': 'something', 'word1': 'something1'}

you could use:

for key,val in to_add.items():
    if key in d:
        d[key] = [d[key],val]

Answer 3

You can create your dictionary assigning a list to each key

d = {'word': [1], 'word1': [2]}

and then use the following synthases to add any value to an existing key or to add a new pair of key-value:

d.setdefault(@key,[]).append(@newvalue)

For your example will be something like this:

d = {'word': [1], 'word1': [2]}
d.setdefault('word',[]).append('something')
d.setdefault('word1',[]).append('something1')
d.setdefault('word2',[]).append('something2')   
print(d)
{'word': [1, 'something'], 'word1': [2, 'something1'], 'word2': ['something2']}

Answer 4

This is what I would do. I hope it helps. If you have a lot of items to add to your dictionary this may not be the fastest route.

d = {'word':1, 'word1':2}

d['word']=[1, 'something']

d['word1']=[2, 'something1']

print(d)

{'word': [1, 'something'], 'word1': [2, 'something1']} 

Answer 5

Thanks for help. I did it that way (thanks to Willem Van Onsem advice):

x = (dict(Counter(tags))) #my dictionary
for i in x:
    color = "#%06x" % random.randint(0, 0xFFFFFF)
    x[i] = [x[i], color]

Answer 6

You could write a function to do this for you:

>>> d = {'word': 1, 'word1': 2}
>>> def set_key(dictionary, key, value):
...     if key not in dictionary:
...         dictionary[key] = value
...     elif type(dictionary[key]) == list:
...         dictionary[key].append(value)
...     else:
...         dictionary[key] = [dictionary[key], value]
... 
>>> set_key(d, 'word', 2)
>>> set_key(d, 'word', 3)
>>> d
{'word1': 2, 'word': [1, 2, 3]}

Alternatively, as @Dan pointed out, you can use a list to save the data initially. A Pythonic way if doing this is you can define a custom defaultdict which would add the data to a list directly:

>>> from collections import defaultdict
>>> d = defaultdict(list)
>>> d[1].append(2)
>>> d[2].append(2)
>>> d[2].append(3)
>>> d
defaultdict(<type 'list'>, {1: [2], 2: [2, 3]})