I have a dictionary like:

```
Data = {
    "weight_factors" : {
        "parameter1" : 10,
        "parameter2" : 30,
        "parameter3" : 30
        },
    "other_info" : {
        }
}

```

I want to get the sum of all values that are under the key `"weight_factors"`:

```
sum = Data["weight_factors"]["parameter1"] + 
      Data["weight_factors"]["parameter2"] + 
      Data["weight_factors"]["parameter3"] 

```

Currently, in order to avoid entering `Data["weight_factors"]` repeatedly, I use the following commands: 

```
d = Data["weight_factors"]
d["parameter1"] + d["parameter2"] + d["parameter3"]

```

But, I guess there should be an operator that does the same thing, without storing `Data["weight_factors"]` as an intermediate variable. I was wondering if such a command or an operator exists.

```
Data["weight_factors"]<unknown operator>(["parameter1"] + 
                                         ["parameter2"] +
                                          ... 
                                         ["parametern"])<unknown operator>

```

**EDIT:**
In the example given above, it was just a sum operation. But it could for example be: 

```
Data["weight_factors"]["parameter1"] * Data["weight_factors"]["parameter2"] + Data[‌​"weight_factors"]["parameter3"]

```

But I do not want enter `Data["weight_factors"]` repeatedly. That's the thing I am searching for... I don't know whether such an operator exists. (In MATLAB, there exists such a thing for cell structures).