CODEWITHSUNDEEP
pythonjson
Jose Ramon
Jose Ramon

Reputation: 5444

Filtering a list of dictionaries using its values in python

I have a list of dictionaries that I would like to filter and create a vector that corresponds to the list values. That list files contains several entries, where each one has a field time, item, state: {values1, value2, value3}. The variable item could take the following 11 values [0.0, 0.1, 0.2, 0.3 ... 1.0]. For each of whose values I would like to find the correspondent value3 values and create a vector of 11 elements where each one should correspond to value3 for the associated item variable. For example if my list is:

my_json = [{'time': datetime.datetime(2018, 7, 4, 13, 42, 55, 613000), 'item': 0.3, 'state': {'value1': 0.0, 'value2': 0.167, 'value3': 0.833}}
{'time': datetime.datetime(2018, 7, 6, 9, 40, 54, 44000), 'item': 0.6, 'state': {'value1': 0.0, 'value2': 0.273, 'value3': 0.727}}
{'time': datetime.datetime(2018, 7, 6, 10, 0, 16, 507000), 'item': 0.5, 'state': {'value1': 0.0, 'value2': 0.0, 'value3': 1.0}}
{'time': datetime.datetime(2018, 7, 6, 10, 37, 16, 769000), 'item': 0.5, 'state': {'value1': 0.0, 'value2': 0.0, 'value3': 1.0}}
{'time': datetime.datetime(2018, 7, 6, 10, 38, 28, 948000), 'item': 0.5, 'state': {'value1': 0.0, 'value2': 0.143, 'value3': 0.857}}
{'time': datetime.datetime(2018, 7, 6, 10, 41, 11, 201000), 'item': 0.4, 'state': {'value1': 0.0, 'value2': 0.091, 'value3': 0.909}}
{'time': datetime.datetime(2018, 7, 6, 11, 45, 25, 145000), 'item': 0.1, 'state': {'value1': 0.0, 'value2': 0.083, 'value3': 0.917}}
{'time': datetime.datetime(2018, 7, 6, 11, 46, 31, 508000), 'item': 0.1, 'state': {'value1': 0.0, 'value2': 0.0, 'value3': 1.0}}
{'time': datetime.datetime(2018, 7, 6, 11, 46, 33, 120000), 'item': 0.1, 'state': {'value1': 0.0, 'value2': 0.214, 'value3': 0.786}}
{'time': datetime.datetime(2018, 7, 6, 12, 36, 25, 695000), 'item': 0.0, 'state': {'value1': 0.0, 'value2': 0.0, 'value3': 1.0}}
{'time': datetime.datetime(2018, 7, 6, 12, 37, 35, 721000), 'item': 0.0, 'state': {'value1': 0.0, 'value2': 0.0, 'value3': 1.0}}]

The desired output of the above example is: [1.0, 0.76, 0.0, 0.833, 0.909, 0.857, 0.727, 0.0, 0.0, 0.0, 0.0] that is keeping also the most recent value (when there are multiple item values) by taking into account time. I have tried to solve it using if-else statements, however, I would like a more elegant solution.

Upvotes: 0

Views: 62

Answers (2)

Pitto
Pitto

Reputation: 8579

I've extended the above solution to include sorting by time in case it is needed

sorted_list = sorted(my_json, key=lambda k: k['time'])    

d = {}
for i in sorted_list:
    d[i['item']] = i['state']['value3']

Upvotes: 1

Barmar
Barmar

Reputation: 780655

Create a dictionary whose keys are the item values. Loop through my_json, assigning value3 to the corresponding element.

d = {}
for i in my_json:
    d[i['item']] = i['state']['value3']

I'm assuming the list is already sorted by the timestamp; if not, sort the list first.

Upvotes: 1

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