iterating through values in a dictionary to invert key and values - python-3.x

Question

I am trying to invert an italian-english dictionary using the code that follows.
Some terms have one translation, while others have multiple possibilities. If an entry has multiple translations I iterate through each word, adding it to english-italian dict (if not already present).
If there is a single translation it should not iterate, but as I have written the code, it does. Also only the last translation in the term with multiple translations is added to the dictionary. I cannot figure out how to rewrite the code to resolve what should be a really simple task
from collections import defaultdict
def invertdict():
source_dict ={'paramezzale (s.m.)': ['hog', 'keelson', 'inner keel'], 'vento (s.m.)': 'wind'}
english_dict = defaultdict(list)
for parola, words in source_dict.items():
if len(words) > 1: # more than one translation ?
for word in words: # if true, iterate through each word
word = str(word).strip(' ')
print(word)
else: # only one translation, don't iterate!!
word = str(words).strip(' ')
print(word)
if word in english_dict.keys(): # check to see if the term already exists
if english_dict[word] != parola: # check that the italian is not present
#english_dict[word] = [english_dict[word], parola]
english_dict[word].append(parola).strip('')
else:
english_dict[word] = parola.strip(' ')
print(len(english_dict))
for key,value in english_dict.items():
print(key, value)
When this code is run, I get :
hog
keelson
inner keel
w
i
n
d
2
inner keel paramezzale (s.m.)
d vento (s.m.)
instead of
hog: paramezzale, keelson: paramezzale, inner keel: paramezzale, wind: vento

Answer 1

It would be easier to use lists everywhere in the dictionary, like:
source_dict = {'many translations': ['a', 'b'], 'one translation': ['c']}
Then you need 2 nested loops. Right now you're not always running the inner loop.
for italian_word, english_words in source_dict.items():
for english_word in english_words:
# print, add to english dict, etc.
If you can't change the source_dict format, you need to check the type explicitly. I would transform the single item in a list.
for italian_word, item in source_dict.items():
if not isinstance(item, list):
item = [item]
Full code:
source_dict ={'paramezzale (s.m.)': ['hog', 'keelson', 'inner keel'], 'vento (s.m.)': ['wind']}
english_dict = defaultdict(list)
for parola, words in source_dict.items():
for word in words:
word = str(word).strip(' ')
# add to the list if not already present
# english_dict is a defaultdict(list) so we can use .append directly
if parola not in english_dict[word]:
english_dict[word].append(parola)