Reverse multiple values with keys in dictionary

Question

I'm quite new to Python and overall programming so bear with me.

What I have is a dictionary of ['Male', 'Female', 'Eunuch'] as values and different names for these as keys:

Persons = { 'Hodor' : 'Male', 'Tyrion': 'Male', 'Theon': 'Male', 'Arya': 'Female', 'Daenerys': 'Female', 'Sansa': 'Female', 'Varys': 'Eunuch}

I want to order them into { Gender: {Names: Counts}}

As such:

input: lst = ['Hodor', 'Hodor', 'Tyrion', 'Tyrion', 'Tyrion', 'Arya', 'Daenerys', 'Daenerys', 'Varys']

output: {'Male': {'Hodor': 2, 'Tyrion': 3, Theon: 0}, 'Female': {'Arya': 1, 'Daenerys': 2, 'Sansa': 0}, 'Eunuch': {'Varys': 1}}

The first thing I have tried is making a code for counting:

counts = {}
for key in Persons: 
    counts[key] = 0 

for key in lst:
    counts[key] += 1

My dictionary D now contains the counts, but how do I compute them all together?

Names = Persons.keys() Gender = Persons.values() Counts = counts.values() Names = counts.keys()

If varys isn't mentioned the gender 'Eunuch' shouldn't be in the output. I've tried different things, but when I try to connect them. I try to switch keys with values, but then only one name comes up.

Hope it makes sense of what I want to do :)

Edit: If Sansa isn't mention and other females are her value should be 0. And I want to be able to manipulate the numbers. Say at what percentage is Hodor mentioned compared to all the males.

Answer 1

Consider

from collections import Counter

cnt = Counter(lst)
print {gender: {name: cnt[name] for name in persons if persons[name] == gender}
          for gender in set(persons.values())}

# {'Eunuch': {'Varys': 1}, 
# 'Male': {'Tyrion': 3, 'Hodor': 2, 'Theon': 0}, 
# 'Female': {'Daenerys': 2, 'Arya': 1, 'Sansa': 0}}

To calculate percentages let's add a helper function:

def percentage_dict(d):
    s = float(sum(d.values()))
    return {k: 100 * v / s for k, v in d.items()}

and then

print {gender: percentage_dict({name: cnt[name] for name in persons if persons[name] == gender})
       for gender in set(persons.values())}

# {'Eunuch': {'Varys': 100.0}, 'Male': {'Hodor': 40.0, 'Theon': 0.0, 'Tyrion': 60.0}, 'Female': {'Daenerys': 66.66666666666667, 'Arya': 33.333333333333336, 'Sansa': 0.0}}

And this is how to write this comprehension more efficiently using a helper function:

def invert(d):
    """Turn {a:x, b:x} into {x:[a,b]}"""
    r = {}
    for k, v in d.items():
        r.setdefault(v, []).append(k)
    return r

and then

cnt = Counter(lst)
print {gender: {name: cnt[name] for name in names}
       for gender, names in invert(persons).items()}

To exclude subdicts that sum up to zero

print {gender: {name: cnt[name] for name in names}
    for gender, names in invert(persons).items()
    if any(cnt[name] for name in names)
}

Answer 2

from collections import defaultdict

gender = {
    'Hodor' : 'Male',
    'Tyrion': 'Male',
    'Theon': 'Male',
    'Arya': 'Female',
    'Daenerys': 'Female',
    'Sansa': 'Female',
    'Varys': 'Eunuch'
}

lst = ['Hodor', 'Hodor', 'Tyrion', 'Tyrion', 'Tyrion', 'Arya', 'Daenerys', 'Daenerys', 'Varys']

result = defaultdict(lambda: defaultdict(int))
for name in lst:
    result[gender[name]][name] += 1