Replace keys with values in a dictionary

Question

Newbie question in dictionaries.

I'm trying to replace keys with values without using iteritems like I've seen in some answers here.

I have 2 dictionaries. One with stuff in it and an empty one. I'd like to keep the first one as is, but print out the second one with the the keys and values replaced from the first one.

So for example:

d1 = {1:"hello", 2 : 10, 3 : 100.0}

The print of d2 will be "hello":1, 10:2, 100.0:3

This is my try:

d1 = {1:"hello", 2 : 10, 3 : 100.0}
d2 = {}
for k in d1:
    d2[d1[k]] == d2[k]
print(d2)

I'm not quite sure where I'm wrong.

Why not with `.items` like this `{v:k for k,v in d1.items()}`? — shaik moeed, Jun 30 '19 at 09:37
Keep in mind not all values can be dictionary keys. What are you trying to achieve by doing this key/value swap? — GordonAitchJay, Jun 30 '19 at 09:39
in general seems like a bad idea, but replace `d2[d1[k]] == d2[k]` with `d2[d1[k]] == k` — Omer Ben Haim, Jun 30 '19 at 09:43

score 3 · Answer 1 · answered Jun 30 '19 at 09:49

3

try this code:

 d1 = {1:"hello", 2 : 10, 3 : 100.0} 

d2 = dict([(value, key) for key, value in d1.items()]) 

for i in d2: 
    print(i, " :  ", d2[i])

answered Jun 30 '19 at 09:49

İsa GİRİŞKEN

216
1
9

score 2 · Accepted Answer · answered Jun 30 '19 at 09:55

2

Your code need slight altering to get it to work as intended:

d1 = {1:"hello", 2 : 10, 3 : 100.0}
d2 = {}
for k in d1.keys():
    d2[d1[k]] = k
print(d2) # {'hello': 1, 10: 2, 100.0: 3}

Keep in mind however that values in dict might repeat, while keys can not (must be unique), so if any value will appear more than once in d1, after such operation you will have fewer elements in d2.

answered Jun 30 '19 at 09:55

Daweo

31,313
3
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Thanks! So all it took was to change the `d2[k]` to just `k` I guess – Daniel Jun 30 '19 at 10:05

score 1 · Answer 3 · answered Jun 30 '19 at 10:30

1

You can also use .items() :-

d1 = {1:"hello", 2 : 10, 3 : 100.0}
d2 = {}
for key, value in d1.items():
    d2[value] = key
print(d2)

I hope it may help you.

answered Jun 30 '19 at 10:30

Rahul charan

765
7
15

Replace keys with values in a dictionary

3 Answers3