Why my dictionary comprehension only change the first key/value

Question

I'm new to python and I wonder why this simple code does not return all the 3 keys/values of my dictionary ? I am trying to create a dictionary and then reverse it .

employees = ['Kelly', 'Emma', 'John']

myNewDict1=dict.fromkeys(employees,"Hi")

newDict2 = { ky: vl for vl, ky in myNewDict1.items() } 

print(newDict2.items())

Here is what I see as result in my terminal :

dict_items([('Hi', 'John')])

While I expect to see all the three keys/values reversed .

You can only have one value for a given key in a dictionary. — jonrsharpe, May 26 '21 at 08:23
"While I expect to see all the three keys/values reversed." What would you expect the value of ``newDict2["Hi"]`` to be, then? — MisterMiyagi, May 26 '21 at 08:26
Try this way, `newDict2 = {'Hi': employees } print(newDict2.items())` Only this is possible.. — Nanthakumar J J, May 26 '21 at 08:28
@NanthakumarJJ Exactly that was the problem, thanks for your help. — 4seasonn, May 26 '21 at 08:39

score 2 · Accepted Answer · answered May 26 '21 at 08:31

Try this approach, using a dictionary it's not possible but you can use a tuple..

employees = ['Kelly', 'Emma', 'John']
print([('Hi', emp) for emp in employees])

Or One liner,

print(list(map(lambda x: ('Hi',x), ['Kelly', 'Emma', 'John'])))

Output:

[('Hi', 'Kelly'), ('Hi', 'Emma'), ('Hi', 'John')]

Why my dictionary comprehension only change the first key/value

1 Answers1