> ## Documentation Index
> Fetch the complete documentation index at: https://docs.activeviam.com/llms.txt
> Use this file to discover all available pages before exploring further.

# atoti.switch()

### atoti.switch(subject, cases, /, \*, default=None)

Return a measure equal to the value of the first case for which *subject* is equal to the case’s key.

*cases*’s values and *default* must either be all numerical, all boolean or all objects.

* **Parameters:**
  * **subject** (*VariableMeasureConvertible*) – The measure or level to compare to *cases*’ keys.
  * **cases** (*Mapping* \*\[\**MeasureConvertible* *|* *None* *|* *AbstractSet* \*\[\**MeasureConvertible* *|* *None* *]* *,* *MeasureConvertible* *]*) – A mapping from keys to compare with *subject* to the values to return if the comparison is `True`.
  * **default** (*MeasureConvertible* *|* *None*) – The measure to use when none of the *cases* matched.
* **Return type:**
  MeasureDefinition

### Example

```pycon theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
>>> df = pd.DataFrame(
...     columns=["Id", "City", "Value"],
...     data=[
...         (0, "Paris", 1.0),
...         (1, "Paris", 2.0),
...         (2, "London", 3.0),
...         (3, "London", 4.0),
...         (4, "Paris", 5.0),
...         (5, "Singapore", 7.0),
...         (6, "NYC", 2.0),
...     ],
... )
>>> table = session.read_pandas(df, keys={"Id"}, table_name="Switch example")
>>> cube = session.create_cube(table)
>>> l, m = cube.levels, cube.measures
>>> m["Continent"] = tt.switch(
...     l["City"],
...     {
...         frozenset({"Paris", "London"}): "Europe",
...         "Singapore": "Asia",
...         "NYC": "North America",
...     },
... )
>>> cube.query(m["Continent"], levels=[l["City"]])
               Continent
City
London            Europe
NYC        North America
Paris             Europe
Singapore           Asia
>>> m["Europe & Asia value"] = tt.agg.sum(
...     tt.switch(
...         m["Continent"],
...         {frozenset({"Europe", "Asia"}): m["Value.SUM"]},
...         default=0.0,
...     ),
...     scope=tt.OriginScope({l["Id"], l["City"]}),
... )
>>> cube.query(m["Europe & Asia value"], levels=[l["City"]])
          Europe & Asia value
City
London                   7.00
NYC                       .00
Paris                    8.00
Singapore                7.00
>>> cube.query(m["Europe & Asia value"])
  Europe & Asia value
0               22.00
```

<Callout icon="link">
  **See also**:
  [`atoti.where()`](./atoti.function.where#atoti.where).
</Callout>