Hatox - 5 months ago 29

Python Question

I'm trying to get a method that gets 3 lists and turns them into a nested dict.

The first and the second list can have any amount of entries > 0.

The values list always has

`len(firstlist) * len(secondlist)`

For example:

`givenlist1 = ["First", "Second"]`

givenlist2 = ["A.B.D", "A.Y.Z", "A.B.E"]

Values = ["10", "2", "3", "4", "1", "3"]

Should return a dict like this:

`{'First': {'A': {'B': {'D': '10', 'E': '3'}, 'Y': {'Z': '2'}}},`

'Second': {'A': {'B': {'D': '4', 'E': '3'}, 'Y': {'Z': '1'}}}}

I tried a lot with

`.update`

Answer

You can use `itertools.product`

to get the required combinations of the entries in `givenlist1`

and `givenlist2`

, and use `zip`

to associate them with the corresponding items from `values`

. Then you need to `.split`

the individual letter keys from the letters in the `givenlist2`

items to get the nested keys, creating new dicts as necessary.

```
from itertools import product
from pprint import pprint
givenlist1 = ["First", "Second"]
givenlist2 = ["A.B.D", "A.Y.Z", "A.B.E"]
values = ["10", "2", "3", "4", "1", "3"]
result = {k1: {} for k1 in givenlist1}
for (k1, k2), v in zip(product(givenlist1, givenlist2), values):
d = result[k1]
keys = k2.split('.')
for k in keys[:-1]:
d = d.setdefault(k, {})
d[keys[-1]] = v
pprint(result)
```

**output**

```
{'First': {'A': {'B': {'D': '10', 'E': '3'}, 'Y': {'Z': '2'}}},
'Second': {'A': {'B': {'D': '4', 'E': '3'}, 'Y': {'Z': '1'}}}}
```

Here's a less compact but possibly more readable way to write the inner `for`

loop:

```
for k in keys[:-1]:
if k not in d:
d[k] = {}
d = d[k]
```