two for loop not working properly in dict comprehension

recipe = {
    "butter chicken" : "Value",
    "pepper chicken" : "Value",
    "garlic chicken" : "Value",
    "ginger chicken" : "Value",
    }

dict comprehension is

{key : value for key in range(1, len(recipe)+1) for value in recipe}   

this is printing

{1: 'ginger chicken', 2: 'ginger chicken', 3: 'ginger chicken', 4: 'ginger chicken'}

actually i want

{1: 'butter chicken', 2: 'pepper chicken', 3: 'garlic chicken', 4: 'ginger chicken'}

>Solution :

You can use enumerate for this:

listrecipe = dict(enumerate(recipe, 1))

Output:

{1: 'butter chicken', 2: 'pepper chicken', 3: 'garlic chicken', 4: 'ginger chicken'}

If you prefer dict-comprehension with range, then it should be:

{key: value for key, value in zip(range(1, len(recipe)+1), recipe)}

Why your solution isn’t working?

listrecipe = {key : value for key in range(1, len(recipe)+1) for value in recipe}   

is equivalent to:

listrecipe = {}

for key in range(1, len(recipe)+1):
    for value in recipe:
        listrecipe[key] = value

So for each key (from 1 to len(recipe)+1) you write each value, so each next value overrides the previous one. That’s why only last value is left for every key.