CODEWITHSUNDEEP
pythonsortingdictionary
cppnoob
cppnoob

Reputation: 129

Sorting a dictionary of lists based on values of another dictionary

I have a dictionary of lists of the form:

dict1 = { key1 : ['a', 'b'], key2: ['c', 'd'], key3: ['e']}

I have another dictionary which is of the form

dict2 = { a: 10, b: 11, c: 6, d: 15, e: 3}

I want to sort dict1 in reverse order based on values of dict 2, so the result would be something like:

sorted_dict = { key2:['d', 'c'], key1: ['b', 'a'], key3:['e']}

Edit: I need to preserve the order of keys. I could convert this as a tuple as well, which is perfectly acceptable.

Thank you!

Upvotes: 0

Views: 95

Answers (3)

Vishal Singh
Vishal Singh

Reputation: 6234

To sort the dictionary values you can do:

sorted_dict = {
    key: sorted(value, key=lambda x: dict2.get(x, 0), reverse=True)
    for key, value in dict1.items()
}

Then to sort the dictionary(change the order of keys) you can do:

sorted_dict = dict(
    sorted(
        sorted_dict.items(),
        key=lambda x: sum(dict2.get(i, 0) for i in x[1]),
        reverse=True,
    )
)

A side note on the order of keys in dictionary.

Dictionaries preserve insertion order. Note that updating a key does not affect the order. Keys added after deletion are inserted at the end.

Changed in version 3.7: Dictionary order is guaranteed to be insertion order. This behavior was an implementation detail of CPython from 3.6.

Upvotes: 1

thethiny
thethiny

Reputation: 1258

You cannot sort a dictionary but you can sort a list. I suggest a similar approach to what I've done below that would sort the keys after mapping the values from dict2 then creates a new unordered dictionary from the sorted keys.

dict1 = { "key1" : ['a', 'b'], "key2": ['c', 'd'], "key3": ['e']}
dict2 = { "a": 10, "b": 11, "c": 6, "d": 15, "e": 3}
sorted_keys = sorted([key for key in dict1], key=lambda x: sum([dict2[el] for el in dict1[x]]), reverse=True)
sorted_dict = {k: dict1[k] for k in sorted_keys}

This produces

{'key1': ['b', 'a'], 'key2': ['d', 'c'], 'key3': ['e']}

sorted by the mapped value

Upvotes: 0

Yilun Zhang
Yilun Zhang

Reputation: 9018

You can use the key argument in sorted:

sorted_dict = {}

for k in dict1:
    sorted_dict[k] = sorted(dict1[k], key=lambda v: dict2[v], reverse=True)

This gives:

{'key1': ['b', 'a'], 'key2': ['d', 'c'], 'key3': ['e']}

Upvotes: 1

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