CODEWITHSUNDEEP
pythonpython-3.xdictionary
abautista
abautista

Reputation: 2780

How to make a dictionary from a list that contains values that are repeated

I am new to python and I have struggling for a while in trying to convert the following list into a dictionary. 

lst = ['AB_MK1230', 'MK12303', 86.17, 'AB_MK1230', 'MK12302', 89.99, 
'AB_MK1230', 'MK12301', 93.82, 'AB_MK1230', 'MK12301', 94.81, 'AB_MK1230', 
'MK12303', 87.5, 'AB_MK1230', 'MK12302', 94.67, 'AB_MK1230', 'MK12302', 90.32, 
'AB_MK1230',  'MK12303', 89.26, 'AB_MK1230',  'MK12301', 91.75,'AB_MK1230', 
'MK12302', 88.54, 'AB_MK1230', 'MK12303', 92.5,'AB_MK1230', 'MK12301', 93.49, 
'AB_MK1230', 'MK12301', 86.47,'AB_MK1230', 'MK12302', 84.79,'AB_MK1230', 
'MK12303', 86.57,'AB_MK1230', 'MK12301', 79.24,'AB_MK1230', 'MK12302', 80.34, 
'AB_MK1230', 'MK12303', 76.88]

AB_MK1230 is the parent sector and MK12303, MK12301 and MK12302 are the child sectors. My output is to have a dictionary with the key of each child sector and the parent sector and float values as the values for that key, something like the following.

dict = {MK12301: AB_MK1230, 93.82, 94.81, 91.75, 93.49, 86.47, 79.24
        MK12302: AB_MK1230, 89.99, 94.67, 90.32, 88.54, 84.79, 80.34
        MK12303: AB_MK1230, 86.17, 87.50, 89.26, 92.50, 86.57, 76.88 }

I have read some documentation from https://docs.python.org/3/tutorial/datastructures.html?highlight=dictionaries but I still can't figure out the solution.

How can I achieve this?

Upvotes: 0

Views: 63

Answers (1)

user2722968
user2722968

Reputation: 16475

We iterate over the list, unpacking three items at a time in (parent, child, value)-order. Using (parent, child) as a key into a dictionary we then add the value into a set.

import itertools
import collections

lst = ['AB_MK1230', 'MK12303', 86.17, 'AB_MK1230', 'MK12302', 89.99, 
'AB_MK1230', 'MK12301', 93.82, 'AB_MK1230', 'MK12301', 94.81, 'AB_MK1230', 
'MK12303', 87.5, 'AB_MK1230', 'MK12302', 94.67, 'AB_MK1230', 'MK12302', 90.32, 
'AB_MK1230',  'MK12303', 89.26, 'AB_MK1230',  'MK12301', 91.75,'AB_MK1230', 
'MK12302', 88.54, 'AB_MK1230', 'MK12303', 92.5,'AB_MK1230', 'MK12301', 93.49, 
'AB_MK1230', 'MK12301', 86.47,'AB_MK1230', 'MK12302', 84.79,'AB_MK1230', 
'MK12303', 86.57,'AB_MK1230', 'MK12301', 79.24,'AB_MK1230', 'MK12302', 80.34, 
'AB_MK1230', 'MK12303', 76.88]

d = collections.defaultdict(set)
for parent, child, value in itertools.zip_longest(*[iter(lst)]*3, fillvalue=None):
    d[(parent, child)].add(value)

d is now a dictionary like

defaultdict(set,
            {('AB_MK1230', 'MK12301'): {79.24,
              86.47,
              91.75,
              93.49,
              93.82,
              94.81},
             ('AB_MK1230', 'MK12302'): {80.34,
              84.79,
              88.54,
              89.99,
              90.32,
              94.67},
             ('AB_MK1230', 'MK12303'): {76.88,
              86.17,
              86.57,
              87.5,
              89.26,
              92.5}})

It's not entirely clear how your final data structure is supposed to look like. If you only want parent as the top-level key, you can use a nested defaultdict...

Upvotes: 2

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