How to grab a value from a dictionary which contains multiple keys?

Question

I have this dictionary:

 mydict = {'950001,959070,959071,959072,950908,959073': 'value1', '400856,400857,400858,400859,400860,400861': 'value2', '920100': 'value3', '950107,950109,950108': 'value4'}

My question is, how do I obtain value value1 by using only one of the keys e.g 950001?

In other words, I want to do something like:

mydict['950001']

and get printed:

value1

I know I may reverse the keys and values, but in this case it won't work for the script I am working on.

Technically speaking, 950001 is not a key, '950001,959070,959071,959072,950908,959073' is. You'd want to recreate the dictionary with each comma separated int as a key. — Brandon Schabell, Jun 02 '19 at 00:42
your dictionary does not have multiple keys. you would have to search the keys to find one that matches doing a linear search — juanpa.arrivillaga, Jun 02 '19 at 00:44

finefoot · Answer 1 · 2019-06-02T02:11:03.860

A dictionary in Python consist of key-value-pairs. So in your example, one key would be '950001,959070,959071,959072,950908,959073'. In my explanations below, I will call 950001, 959070 and so on just "numbers".

Method 1: You could write a loop over all keys of your dict and split each key into a list at every comma , with str.split. Your list then contains your numbers and you can check if your requested number n is in there:

mydict = {'950001,959070,959071,959072,950908,959073': 'value1', '400856,400857,400858,400859,400860,400861': 'value2', '920100': 'value3', '950107,950109,950108': 'value4'}

n = '950001'
for key in mydict:
    if n in key.split(','):
        print(mydict[key])

Which prints:

value1

Method 2: Alternatively, you could convert your dictionary mydict into a new dictionary new_dict so every number gets its own key:

mydict = {'950001,959070,959071,959072,950908,959073': 'value1', '400856,400857,400858,400859,400860,400861': 'value2', '920100': 'value3', '950107,950109,950108': 'value4'}

new_dict = {}
for key in mydict:
    for new_key in key.split(','):
        new_dict[new_key] = mydict[key]

print(new_dict)

Which prints:

{'950001': 'value1', '959070': 'value1', '959071': 'value1', '959072': 'value1', '950908': 'value1', '959073': 'value1', '400856': 'value2', '400857': 'value2', '400858': 'value2', '400859': 'value2', '400860': 'value2', '400861': 'value2', '920100': 'value3', '950107': 'value4', '950109': 'value4', '950108': 'value4'}

Then you can access your value just like you said with new_dict['950001'].

The code above is written with emphasis on clarity. Depending on your use case, you could write a function and/or use a dict comprehension to make your code look nicer if you're comfortable with that:

mydict = {'950001,959070,959071,959072,950908,959073': 'value1', '400856,400857,400858,400859,400860,400861': 'value2', '920100': 'value3', '950107,950109,950108': 'value4'}
new_dict = {nk: v for k, v in mydict.items() for nk in k.split(',')}
print(new_dict['950001'])

If the same number appears in several keys beware that the alternative solution will only show one of the values — Keatinge, Jun 02 '19 at 00:47
If you do not split them, you are not using your dictionary as a dictionary, you are using it as a list. — Brandon Schabell, Jun 02 '19 at 00:47

score -2 · Answer 2 · answered Jun 02 '19 at 01:07

-2

def get_value(n):
    newdict = {
        "value1": ["950001", "959070", "959071", "959072", "950908", "959073"],
        "value2": ["400856", "400857", "400858", "400859", "400860", "400861"],
        "value3": ["920100"],
        "value4": ["950107", "950109", "950108"]
    }
    # Loop through dictionary to find a match and its value
    for value, nums in newdict.items():
        if n in nums:
            return(value)

answered Jun 02 '19 at 01:07

Aero Blue

518
2
14

Solutions should generalize to any keys and values. Usually the example is just to illustrate the problem – Untitled123 Jun 02 '19 at 01:13
To clarify what @Untitled123 said, the values are not necessarily unique. – wjandrea Jun 02 '19 at 01:27

How to grab a value from a dictionary which contains multiple keys?

2 Answers2