CODEWITHSUNDEEP
pythondictionary
Andrew Donnelley
Andrew Donnelley

Reputation: 11

"Updating" a Dictionary

When given a dictionary(db), is there a way to add values to a key that already exist within the dictionary. Hence the updating or simply adding the key and its value if the key doesn't already exist:

Say that: 

db = {'John': [('Brown', 'Blue', 180)]}
def add_anything(db,Name(the key), HairColor(value), EyeColor(value), Height(value):
add_anything(db, "John", "Black", "Red", "160")

and when i updated db, returning db would give back:

{'John': [('Brown', 'Blue', 180),('Black', 'Red', 160)]}

How would that definition function look like? Thank you

Upvotes: 0

Views: 112

Answers (3)

John Smith
John Smith

Reputation: 1117

Might be missing something here but the faster try/catch (do first then ask forgiveness)?

d = {'John': [('Brown', 'Blue', 180)]}

def add_to_dict(d, k, v):
    try:
        d[k].append(v)
    except KeyError:
        d[k] = [v]
    return d

print(d)
add_to_dict(d, "John", ('Black', 'Red', 160))
print(d)
add_to_dict(d, "Jim", ('Blond', 'Green', 200))
print(d)
add_to_dict(d, "Jim", ('Blond', 'Green', 220))
print(d)

or the slower if check (ask for permission then do)?

def add_to_dict(d, k, v):
    if k in d.keys():
        d[k].append(v)
    else:
        d[k] = [v]
    return d

Upvotes: 0

tdelaney
tdelaney

Reputation: 77337

I think the brute force method is the best. Its still short and straight forward

def add_anything(d, key, *value):
    if key in d:
        if value not in d[key]:
            d[key].append(value)
    else:
        d[key] = [value]

Running a few tests

>>> add_anything(d, 'bob', 'Brown', 'Blue', '180')
>>> d
{'bob': [('Brown', 'Blue', '180')]}
>>> add_anything(d, 'bob', 'Brown', 'Blue', '180')
>>> d
{'bob': [('Brown', 'Blue', '180')]}
>>> add_anything(d, 'bob', 'Brown', 'Blue', '666')
>>> d
{'bob': [('Brown', 'Blue', '180'), ('Brown', 'Blue', '666')]}
>>> add_anything(d, 'jane', 'Brown', 'Blue', '666')
>>> d
{'jane': [('Brown', 'Blue', '666')], 'bob': [('Brown', 'Blue', '180'), ('Brown', 'Blue', '666')]}

Upvotes: 1

Alex Hall
Alex Hall

Reputation: 36023

Using a set to prevent duplicates but at the cost of losing order which I'm assuming isn't important:

>>> from collections import defaultdict
>>> db = defaultdict(set)
>>> db['John'].add(('Brown', 'Blue', 180))
>>> db
defaultdict(<type 'set'>, {'John': set([('Brown', 'Blue', 180)])})
>>> db['John'].add(('Brown', 'Blue', 180))
>>> db
defaultdict(<type 'set'>, {'John': set([('Brown', 'Blue', 180)])})
>>> db['John'].add(("Black", "Red", "160"))
>>> db['Jane'].add(("Red", "Gree", "140"))
>>> db
defaultdict(<type 'set'>, {'Jane': set([('Red', 'Gree', '140')]), 'John': set([('Brown', 'Blue', 180), ('Black', 'Red', '160')])})

Upvotes: 0

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