Python: Average a list and append to dictionary - dictionary

Question

I have a dictionary of names with a number (a score) assigned to them. The file is laid out as so:
Person A,7
Peron B,6
If a name is repeated in the file e.g. Person B occurred on 3 lines with 3 different scores I want to calculate the mean average of these scores then append this result to a dictionary in the form of a list. However, I keep encountering an error when i try to sort the dictionary. Code below.
else:
for key in results:
keyValue = results[key]
if len(keyValue) > 1:
# Line below this needs modification
keyValue = list(sum(keyValue)/len(keyValue))
newResults[key] = keyValue
# Error in above code...
else:
newResults[key] = keyValue
print(newResults)
print(sorted(zip(newResults.values(), newResults.keys()), reverse=True))
Results is a dictionary of the people (the keys) and their scores (the values) where the values are lists so that:
results = {'Bob':[7],'Jane':[8,9]}

Answer 1

If you're using Python 3.x you can use its statistics library which contains a function mean. Now assuming that your dict looks like: results = {'Bob': [7], 'Jane': [8, 9]} you can create a newResults dict like this:
from statistics import mean
newResults = {key: mean(results[key]) for key in results}
This is called dict comprehension and as you can see it's kinda intuitive. Starting with { you're telling that dict is going to be created. Then with key: value you're defining its structure. Lastly, with for loop you iterate over a collection that will be used for the dict creation. You can achieve the same with:
newResults = {}
for key in results:
newResults[key] = mean(results[key])
You want to sort the dict in the end. Unfortunately it's not possible. You can either create an OrderedDict, which remembers the items insertion order or a list which will contain sorted keys to your dict. The latter will look like:
sortedKeys = sorted(newResults, key=lambda x: newResults[x])