CODEWITHSUNDEEP
pythondictionary
Akshan Dua
Akshan Dua

Reputation: 5

How to find value in dictionary using key and then search the value within the tuple(value of dictionary)?

This is the data that I have: You can see that it is a dictionary with a string key and then multiple tuples to it. I am trying to write a lookup function in order to use the key string and the toll string to lookup the value (float).

dict1 = {'20MAY17': [('TOLL2', 9817.73), ('TOLL3', 8395.49)], '23MAY17': [('TOLL2', 6497.36), ('TOLL4', 6827.51)], '13MAY17': [('TOLL4', 9803.42)], '5MAY17': [('TOLL3', 6677.66)], '16MAY17': [('TOLL4', 1565.78), ('TOLL3', 7949.97), ('TOLL2', 3739.91)], '12MAY17': [('TOLL2', 5680.84)], '6MAY17': [('TOLL2', 2420.46)], '28MAY17': [('TOLL3', 6405.19), ('TOLL4', 1358.27)], '22MAY17': [('TOLL4', 4022.52), ('TOLL3', 8823.13)], '11MAY17': [('TOLL4', 4832.2699999999995)], '27MAY17': [('TOLL3', 8878.97)], '17MAY17': [('TOLL4', 4150.74)], '3MAY17': [('TOLL3', 5729.33)], '24MAY17': [('TOLL4', 1452.02), ('TOLL1', 3860.73)], '8MAY17': [('TOLL1', 9863.36)], '18MAY17': [('TOLL1', 4584.25)], '15MAY17': [('TOLL1', 8640.64)]}

The dictionary is called dict1.

Here is the function, I am using user input.

def lookup(dict1, str1, str2):
    print(dict1[str1][str2])

It should do something like this:

lookup(dict1, '20MAY17', 'TOLL2')

9817.73

lookup(dict1, '20MAY17', 'TOLL3')

8395.49

Upvotes: 0

Views: 39

Answers (3)

Anton vBR
Anton vBR

Reputation: 18916

Change the function to:

def lookup(dict1, str1, str2):
    print(dict(dict1.get(str1)).get(str2))

This works because the dict key is converted to a dict before the 2nd key is passed.

Upvotes: 1

timgeb
timgeb

Reputation: 78750

Transform your data structure to a dictionary where the values dictionaries instead of lists of tuples. After that, lookup is trivial.

>>> d = {'20MAY17': [('TOLL2', 9817.73), ('TOLL3', 8395.49)], '23MAY17': [('TOLL2', 6497.36), ('TOLL4', 6827.51)]}
>>> d_better = {k:dict(v) for k,v in d.items()}
>>> d_better
{'20MAY17': {'TOLL2': 9817.73, 'TOLL3': 8395.49}, '23MAY17': {'TOLL4': 6827.51, 'TOLL2': 6497.36}}
>>> 
>>> def lookup(dict_, day, toll):
...     return dict_[day][toll]
... 
>>> lookup(d_better, '20MAY17', 'TOLL2')
9817.73

As you can see, the lookup function is somewhat unwarranted and you could write d_better[day][toll] directly.

Upvotes: 1

Omni
Omni

Reputation: 1022

You can have dictionaries inside dictionaries. I would suggest to simply preprocess your data by (if your original data was stored in original_data)

data = dict((key, dict(tpl)) for key, tpl in original_data.items())

Then you can simply do a lookup by a double item lookup:

data['20MAY17']['TOLL2']

Upvotes: 2

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