From nested for loop to dictionary comprehension?

Question

I have a dictionary (dict_) with lists of integers as values. I want to make an operation on these list and save the result as a new dictionary.

Below I do an operation on these list, adding 2 if the elements are larger than 5. I use a nested for loop to achieve this. How would I achieve the same using dictionary comprehension?

dict_={'a':[5, 8, 7],
      'b':[4, 7, 2],
      'c':[2, 2, 4]}

print(dict_)
#Output: {'a': [5, 8, 7], 'b': [4, 7, 2], 'c': [2, 2, 4]}

dict_new = {}

for k, v in dict_.items():
    list_temp=[]
    for e in v:
        if e > 5:
            ne=e + 2
            list_temp.append(ne)
        else:
            list_temp.append(e)
    
    dict_new[k] = list_temp

print(dict_new)
# Output: {'a': [5, 8, 7], 'b': [4, 7, 2], 'c': [2, 2, 4]}

Answer 1

this could be your dict-comprehension:

{k: [i if i <= 5 else i + 2 for item in v] for k, v in dict_.items()}

note that you need a list-comprehension for the values as well.

noting that False is basically 0 and True is 1 you could simplify (but maybe making it more obscure?) the list-comprehension:

{k: [i + 2 * (i > 5) for i in v] for k, v in dict_.items()}

Answer 2

You can do this, but as you are working with both dicts and lists, you will want to use a list comprehension also.

my_dict ={'a':[5, 8, 7],
  'b':[4, 7, 2],
  'c':[2, 2, 4]}

d = {key: [x if x <= 5 else x + 2 for x in value] for key, value in my_dict.items()}

This should solve the above problem and return:

{'a': [5, 10, 9], 'b': [4, 9, 2], 'c': [2, 2, 4]}

Answer 3

for k, v in dict_.items():
    dict_new[k] = [e + 2 if e > 5 else e for e in v ]