How to increment values for each key in dict?

Question

In Python, how to iterate a dict and increment values of each key?

D = {k1:1, k2:2}

I want D to be {k1:2, k2:3} .

Answer 1

You can use a dict comprehension to increment each value, then assign it back

>>> {k: v+1 for k,v in D.items()}
{'k1': 2, 'k2': 3}

Answer 2

You can either modify (also called "mutate") the dictionary D:

for k in D.keys():
    D[k] = D[k] + 1 

Or you can create a new dictionary and re-assign D to it:

D = { k: v+1 for k, v in D.items() }

The difference will become apparent if something else points at D, or if D is very large and takes longer to re-create than to update in-place.

Answer 3

D = {"k1":1, "k2":2}

for i in D:
  D[i] += 1

print(D)

Seems to do the trick, I wasnt sure on the k1 / k2 so i made them strings for testing

Answer 4

I have another solution for you, I hope it is useful.

for key in D:
    D[key] +=1