Output a dictionary based on inputs from another dictionary and two lists

Question

I have a dictionary and two lists and would like to output another dictionary that contains the individual list as the title and sum of the list contents as the values however, I have no clue as to how I could do this.

results = {'Apple':'14.0', 'Banana':'12.0', 'Orange':'2.0', 'Pineapple':'9.0'}

ListA = ['Apple','Pineapple']
ListB = ['Banana','Orange']

Output:

dicttotal = {'ListA':'23.0', 'ListB':'14.0'}

Edit: I have decided to use pandas to work with the above data as I find that the simplicity of pandas is more suited for my level of understanding. Thanks for the help everyone!

Answer 1

in python you can use list comprehensions to make this easy to read:

items_for_a = [float(v) for i, v in results.items() if i in ListA]
total_a = sum(items_for_a)

the dicttotal you want to print is strange, though. I don't think you want to print variable names as dictionary keys.

in python2 you should use .iteritems() instead of .items()

Answer 2

You can use fllowing code get ListA's sum. The same way for ListB. Just try it yourself

dicttotal = {}
ListASum = 0.0
ListBSum = 0.0
for item in ListA:
    if item in results:
        ListASum += float(results[item])
dicttotal['ListA'] = ListASum

Answer 3

Reduce and dictionary comprehension to create dictionary with an initial value, followed by updating a single value. Had key names not been variable names maybe could have done dict comprehension for both.

from functools import reduce
d_total = {'ListA': str(reduce(lambda x, y: float(results[x]) + float(results[y]), lista))}
d_total['ListB'] = str(reduce(lambda x, y: float(results[x]) + float(results[y]), listb))

 {'ListA': '23.0', 'ListB': '14.0'} 

Note: PEP-8 snake_case for naming

Answer 4

一线使用（丑陋的） eval()函数，但是正如Eduard所说，最好不要将变量名用作键：

{list_name: str(sum([float(results[item]) for item in eval(list_name)])) for list_name in ['ListA', 'ListB']}