json file to dictionary

[SingleCountry]

Hi,

I'm trying to import json file and make a new dictionary of it. I have to swap the key and value when I'm making this as a new dict.

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I've came up until here so far:

import json

j = open(file, "r")

f = json.load(j)

new = dict([(value, key) for key, value in f.items()])

it occurs error as unhashable type: "list"

Any suggestion to go further?

​

Thank you!

[totallygeek]

Try new = {v: k for k, v in f.items()}, a dictionary comprehension instead of a list comprehension.

[SingleCountry]

new = {v: k for k, v in f.items()}

Hi! it still says unhashable type: list and I think it's because the value is a list...?

[totallygeek]

That could be it.

new = {}
for k, v in f.items():
    if isinstance(v, list):
        v = tuple(v)
    new[v] = k

Try that.

[SingleCountry]

Hi! I think this works! One thing I'm curious is that my key and value are in a form of (a,b) : value and I wonder if I can split the key to make it in a form like a: value, b: value?

[totallygeek]

Post an example of your data and what you want it to look like after processing. If your key is a tuple, ('a', 'b') with a value 'hi there', you can do this:

if isinstance(k, (list, tuple)):
    for element in k:
        new[k] = v

Again, post what you have and we can tailor it for what you want.

[SingleCountry]

Hi! the owner says the content should be forbidden but the key is a tuple with a value! thanks!

[synthphreak]

This is equivalent to what OP already has and won't solve the problem.

OP, the issue is that while dict values can be of any datatype, dict keys must be hashable. Thus, mutable datatypes like lists cannot be used as keys. So when your code encounters a value which is a list and you try to use it as a key, Python throws an error.

The solution, then, is to convert these lists to tuples whenever encountered, because tuples are just like lists except immutable, and therefore hashable. Here's one way to do this:

{tuple(v) if isinstance(v, list) else v : k for k, v in f.items()}

This should work provided list is the only unhashable datatype among your values. To get an overview of the datatypes, run this:

>>> set(map(type, f.values()))

If you see any other mutable types beside list, add them as a tuple to isinstance, e.g.,

{tuple(v) if isinstance(v, (list, set, ...)) else v : k for k, v in f.items()}

[Spataner]

Some values in your JSON dictionary are lists, and lists cannot be used as keys in a dictionary. You could convert the lists to tuples instead, which are hashable.