CODEWITHSUNDEEP
pythonlistdictionarynested
fiticida
fiticida

Reputation: 694

Find a nested dict inside a list

I have a list of nested dictionaries that is a cached for finding returned results from a BBDD.

What I want is to check if a nested dict exists inside my list and return the value it has.

My dict had this structure:

cached_list= [{'session':'2019-02-03',
               'country':'spain',
               'isin': 'ES202121223'} , ...
}

For avoiding going throw all the values I did a nested dict inside my cached list:

list_cached = [{'2019-02-03':{'spain':'ES202121223'}} , ...]

As you can see it has the same structure but I am using key as values for checking if that structure exists.

My problem is that I am saving all that nested dict inside a list, and I dont know how to check if that structure exists in my list of nested dictionaries.

Any idea for solving it?

Thanks.

Upvotes: 0

Views: 605

Answers (2)

9769953
9769953

Reputation: 12201

Adding an example answer with Pandas (not really an answer, but an example for handling a list of dicts, and using a multi-index to create the idea of a nested dict.)

>>> cached_list = [{'session': '2019-02-03', 'country': 'spain', 'isin': 'ES202121223'},
...                {'session': '2019-02-03', 'country': 'italy', 'isin': 'IT202121223'}]
>>> import pandas as pd
>>> df = pd.DataFrame(cached_list)
>>> df
      session country         isin
0  2019-02-03   spain  ES202121223
1  2019-02-03   italy  IT202121223
>>> df = df.set_index(df.index, 'session')
>>> df
      session country         isin
0  2019-02-03   spain  ES202121223
1  2019-02-03   italy  IT202121223

>>> df['session'] = pd.to_datetime(df['session'])
>>> from datetime import datetime
>>> df[df['session'] == datetime(2019, 2, 3)]
     session country         isin
0 2019-02-03   spain  ES202121223
1 2019-02-03   italy  IT202121223

The set_index part is not really necessary: leaving it out will just select directly on a data column.

Upvotes: 1

9769953
9769953

Reputation: 12201

Not the prettiest solution, but a variation on the following list-comprehension could work:

>>> list_cached = [{'2019-02-03':{'spain':'ES202121223'}}, 1, {'a': 1} ]
>>> [item for item in list_cached if isinstance(item, dict) and isinstance(list(item.values())[0], dict)]
[{'2019-02-03': {'spain': 'ES202121223'}}]

The two isinstance clauses check if an item is a nested dict. Note that this still fails for an empty nested dict ({'2019-02-03': {}}).

Upvotes: 1

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