从由元组组成的字典中删除元素，计算元组中的最后一个元素和字典中的值

Question

The following dictionary is given:

a = {('a','b', 'c'):3,('a','d','c'):4, ('f','e','b'):5, ('r','t','b'):5.1}

The dictionary consists of tupels as a key and numbers as a value. Each tuple consists of a series of letters. From all the tuples whose last element is the same one should exclude those whose dictionary value is the lowest. For example the tuple ('a','b', 'c') and the tuple ('a','d','c') Both have the letter C as the last element, therefore the one whose value is the lowest should be removed. With reference to the above dictionary the result should be:

{('a','d','c'):4, ('r','t','b'):5.1}

Answer 1

You could do:

from collections import defaultdict
from operator import itemgetter

a = {('a','b', 'c'):3,('a','d','c'):4, ('f','e','b'):5, ('r','t','b'):5.1}

# group the items by the last element of the key of the tuple
lookup = defaultdict(list)
for key, value in a.items():
    lookup[key[2]].append((key, value))

# find the maximum in each group by the value of the tuple
result = dict(max(value, key=itemgetter(1)) for value in lookup.values())

print(result)

Output

{('a', 'd', 'c'): 4, ('r', 't', 'b'): 5.1}

Answer 2

Code:

a = {('a','b', 'c'):3,('a','d','c'):4, ('f','e','b'):5, ('r','t','b'):5.1}

keys_to_remove = []
for key in a.keys():
    srch_key = key[-1]
    lowest_val = min(v for k,v in a.items() if k[-1] == srch_key)
    keys_to_remove.append(*(k for k,v in a.items() if k[-1] == srch_key and v == lowest_val))
    
for key_to_remove in set(keys_to_remove):
    a.pop(key_to_remove)
print(a)
        

Output:

{('a', 'd', 'c'): 4, ('r', 't', 'b'): 5.1}

Answer 3

Another solution might be:

a_dict = {('a','b', 'c'):3,('a','d','c'):4, ('f','e','b'):5, ('r','t','b'):5.1}


b_dict = dict()
seq = 2
for key in a_dict:
    b_key = find_key(b_dict, key[seq])
    if b_key is not None:
        b_dict.pop(b_key)
        b_dict[key] = a_dict[key]
    else:
        b_dict[key] = a_dict[key]


def find_key(x_dict, k, seq=2):
    for key in x_dict:
        if key[seq] == k:
            return key
    return None

Create an empty dictionary. Iterate over the dict, search the last element of the key tuple in new dict. Add the key:value to new dict if not exists. If found any, check if its value is greater or not. If it is not, delete the element and add the new key:value.