Reversing the key values in a dictionary (advanced reverse string in Python)

Question

So what I was trying to do was output the string "33k22k11k", which is just the last value followed by the reversed last key followed by the second last value followed by the second last reversed key and so on. I'm not sure how to get the reversed key value for the specific loop that I am in. From the code I currently I have, I get the output:

dict = {"k1":1, "k2":2, "k3":3}
current=""
current_k=""
for k,v in dict.items():
    for i in k:
        current_k=i+current_k
    current=str(v)+current_k+current
print(current)
print(current_k)

33k2k1k22k1k11k

3k2k1k

If any of the answers solved your problem, please mark it as accepted for the future references. — Chris
– Chris, Commented Feb 22, 2019 at 10:54

Chris · Accepted Answer · 2018-12-26 08:24:13Z

3

Edited

First of all, if you are on python < 3.6, dict does not keep the order of items. You might want to use collections.OrderedDict for your purpose.

d = {"k1":1, "k2":2, "k3":3}
d.keys()
# dict_keys(['k2', 'k1', 'k3'])

whereas,

d = OrderedDict()
d['k1'] = 1
d['k2'] = 2
d['k3'] = 3
d.keys()
# odict_keys(['k1', 'k2', 'k3'])

With our new d, you can either add the key and values and reverse it:

res = ''
for k, v in d.items():
    res += str(k) + str(v)
res[::-1]
# '33k22k11k'

or reversely iterate:

res = ''
for k, v in reversed(d.items()):
    res +=  str(v)[::-1] + str(k)[::-1]
res
# '33k22k11k'

edited Dec 26, 2018 at 8:24

answered Dec 26, 2018 at 8:10

Chris

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2 Comments

iBug Over a year ago

No. Python 3.6 and up have built-in dict() ordered.

Chris Over a year ago

@iBug I'm aware of the change, but since OP didn't specify the python version, OrderedDict can work on any version, where as dict can't. I'll still edit to make it more clear.

Sam Hollenbach · Accepted Answer · 2018-12-26 08:00:19Z

0

I may be wrong but it seems like you would want to reset the value of current_k each time you access a new key

dict = {"k1":1, "k2":2, "k3":3}
current=""
for k,v in dict.items():
    current_k=""
    for i in k:
        current_k=i+current_k
    current=str(v)+current_k+current
print(current)
print(current_k)

answered Dec 26, 2018 at 8:00

Sam Hollenbach

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Comments

U13-Forward · Accepted Answer · 2018-12-26 08:13:10Z

0

Why not simply do:

print(''.join([a+str(b) for a,b in dict.items()])[::-1])

Output:

"33k22k11k"

But if the values are different from the keys, do:

print(''.join([str(b)[::-1]+a for a,b in dict.items()[::-1]]))

edited Dec 26, 2018 at 8:13

answered Dec 26, 2018 at 8:08

U13-Forward

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1 Comment

Mark Over a year ago

doesn't that reverse the values as well?

Rishabh · Accepted Answer · 2018-12-26 09:22:56Z

0

You can use the Python map function to create the reversed string(using f-string) for each key/value pair and then join it.

dict1 = {"k1":1, "k2":2, "k3":3}
new_dict =  "".join(map(lambda k, v: f'{k}{v}'[::-1] , dict1.keys(), dict1.values()))

Output:

33k22k11k

answered Dec 26, 2018 at 9:22

Rishabh

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Comments

Niladri Basu · Accepted Answer · 2018-12-28 07:05:39Z

0

You can do something like this perhaps:

dict = {"k1":1, "k2":2, "k3":3}
print("".join(list(reversed([str(v)+"".join(reversed(k)) for k, v in dict.items()]))))

Output:

33k22k11k

edited Dec 28, 2018 at 7:05

answered Dec 26, 2018 at 8:15

Niladri Basu

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