How to add a new key to an existing dictionary and append previous key as value to the new key creat-CodePudding

I have a json format data in a list like below:-

lis_t=[{'score': 76, 'steps': [{'score': 49, 'len': 261}, {'score': 27, 'len': 172}, {'score': 0, 'len': 0}]},
{'score': 82,'steps': [{'score': 82, 'len': 484}, {'score': 0, 'len': 0 }]}, 
{'score': 51, 'steps': [{'score': 51, 'len': 268}, {'score': 0, 'len': 0},{'score': 16, 'len': 75}, {'score': 187, 'len': 47}]}]

From this list I want to add a new key details in the value of key steps and append only the score key as a value to the new key. The output I am excepting is as follow:-

    output =[{'score': 76, 'steps': [{'details':{'score': 49}, 'len': 261,'details': {'score': 27}, 'len': 172,'details': {'score': 0}, 'len': 0}]},
{'score': 82, 'steps': [{'details':{'score': 82}, 'len': 484, 'details':{'score': 0}, 'len': 0 }]}, 
{'score': 51, 'steps': [{'details':{'score': 51}, 'len': 268,'details': {'score': 0}, 'len': 0,'details':{'score': 16}, 'len': 75, 'details':{'score': 187}, 'len': 47}]}]

Now, I tried to create a new key details and tried to append the value but it says that the dictionary size is changed while iterating. To avoid this I have used list(j.keys()) but if I use this then I wont be able to access the value of that dictionary. Is there any better way of solving this issue?

for i in lis_t:
    for k,v  in i.items():
        if k == 'steps':
            for j in v:
                for key,val in j.items():
                    j['details']=val
                    print(key)

Error:

RuntimeError: dictionary changed size during iteration

Excepted Output:-

    output=[{'score': 76, 'steps': [{'details':{'score': 49}, 'len': 261,'details': {'score': 27}, 'len': 172,'details': {'score': 0}, 'len': 0}]},
{'score': 82, 'steps': [{'details':{'score': 82}, 'len': 484, 'details':{'score': 0}, 'len': 0 }]}, 
{'score': 51, 'steps': [{'details':{'score': 51}, 'len': 268,'details': {'score': 0}, 'len': 0,'details':{'score': 16}, 'len': 75, 'details':{'score': 187}, 'len': 47}]}]

CodePudding user response：

I would use a list comprehension to reset the "steps" value. Maybe something like:

lis_t = [
    {
        'score': 76,
        'steps': [
            {'score': 49, 'len': 261},
            {'score': 27, 'len': 172},
            {'score': 0, 'len': 0}
        ]
    },
    {
        'score': 82,
        'steps': [
            {'score': 82, 'len': 484},
            {'score': 0, 'len': 0 }
        ]
    }, 
    {
        'score': 51,
        'steps': [
            {'score': 51, 'len': 268},
            {'score': 0, 'len': 0},
            {'score': 16, 'len': 75},
            {'score': 187, 'len': 47}
        ]
    }
]

for item in lis_t:
    item["steps"] = [
        {"details": {"score": step_item["score"]}, "len": step_item["len"]}
        for step_item in item["steps"]
    ]

import json
print(json.dumps(lis_t))

This gives:

[
    {
        "score": 76,
        "steps": [
            {"details": {"score": 49}, "len": 261},
            {"details": {"score": 27}, "len": 172},
            {"details": {"score": 0}, "len": 0}
        ]
    },
    {
        "score": 82,
        "steps": [
            {"details": {"score": 82}, "len": 484},
            {"details": {"score": 0}, "len": 0}
        ]
    },
    {
        "score": 51,
        "steps": [
            {"details": {"score": 51}, "len": 268},
            {"details": {"score": 0}, "len": 0},
            {"details": {"score": 16}, "len": 75},
            {"details": {"score": 187}, "len": 47}
        ]
    }
]

Which is what I think you are after.