Ranking values in a Dictionary (and taking care of ex-aequos correctly)

问题

I would like to rank the values in a dictionary.

For instance, I have this dictionary: {"A": 10, "B: 3, "C": 8, "D": 3, "E": 2} The result should look like: {"E": 1, "B": 2, "D": 2, "C": 4, "A": 5}

Please note that D is ranked as fourth because B and D are tied at position two. Hence, there is no position three.

Similar solutions have already been given in other threads, however they did not take into account ex-aequo positions in the traditional way: Adding a rank to a dict in python and Python Ranking Dictionary Return Rank

回答1:

First sort the data in ascending order based on the number, like this

>>> data = {"A": 10, "B": 3, "C": 8, "D": 3, "E": 2}
>>> s_data = sorted(data.items(), key=lambda item: item[1])
>>> s_data
[('E', 2), ('D', 3), ('B', 3), ('C', 8), ('A', 10)]

Now, for every element processed,

if it is not the same as the previous element then the rank should be incremented by the number of similar elements processed till now
if it is the same, then simply count the current element as a similar element

To implement this, initialize few variables, like this

>>> rank, count, previous, result = 0, 0, None, {}

then keep checking if the current element is not equal to the previous element and if it is true, increment rank by the number of times the similar elements occured.

>>> for key, num in s_data:
...     count += 1
...     if num != previous:
...         rank += count
...         previous = num
...         count = 0
...     result[key] = rank

Now, result will have the result you wanted.

>>> result
{'D': 2, 'C': 4, 'E': 1, 'B': 2, 'A': 5}

来源：https://stackoverflow.com/questions/32908613/ranking-values-in-a-dictionary-and-taking-care-of-ex-aequos-correctly

标签

python

sorting

dictionary

ranking