<s>[INST] I'd like to know how to map multiple values of the same field in one document of Elasticsearch to a script.
The data is something like this:

```
{
  "id": 1,
  "cities": ["New York", "Los Angeles", "Seattle"]
}
```

Now, I should write a script that can access each city value and perform some calculations based on that and maybe other fields too (e.g. "id").

I should be able to access other fields (e.g. "id") inside my script too.
Here is what I've tried so far:

```
{
  "script": {
    "source": "for(city in doc['cities']) { ... }"
  }
}
```

I don't know how to access other fields (e.g. "id") though.

In the script you provide, could you also add some form of aggregation based on "cities"?[/INST]