CODEWITHSUNDEEP
pythonjsonpython-3.xdictionarytypeerror
James
James

Reputation: 1972

Retreive JSON Keys In Python

My goal is to iterate through every element in classes and add the value of class in classes into a new list.

JSON Structure:

{
    "images": [
      {
        "classifiers": [
          {
            "classes": [
              {
                "class": "street",
                "score": 0.846
              },
              {
                "class": "road",
                "score": 0.85
              }
            ]
          }
        ]
      }
   ]
}

In the above JSON example, the new list should contain:

{'street','road'}

I tried to iterate over json_data['images'][0]['classifiers']['classes'] and for each one list.append() the value of class.

list = list()
def func(json_data):
    for item in json_data['images'][0]['classifiers']['classes']:
        list.append(item['class'])
    return(list)

I am receiving a TypeError which is: 

TypeError: list indices must be integers or slices, not str

What I am getting from this TypeError is that it attempts to add a string to the list but list.append() does not accept a string as a paramet. I need to somehow convert the string into something else.

My question is what should I convert the string into so that list.append() will accept it as a parameter?

Upvotes: 1

Views: 255

Answers (1)

roganjosh
roganjosh

Reputation: 13175

The first issue is that classifiers is also a list, so you need an additional index to get at classes. This will work: 

for item in json_data['images'][0]['classifiers'][0]['classes']:

Second, you want the result as a set not a list, so you can do: return set(lst). Note that sets are unordered, so don't expect the ordering of items to match that of the list.

Upvotes: 3

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