> ## Documentation Index
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# atoti.Cube.create_date_hierarchy()

#### Cube.create\_date\_hierarchy(name, \*, column, levels=frozendict(\{'Year': 'y', 'Month': 'M', 'Day': 'd'}))

Create a multilevel date hierarchy based on a date column.

The new levels are created by matching a [date pattern](https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/time/format/DateTimeFormatter.html#patterns).
Here is a non-exhaustive list of patterns that can be used:

| Pattern | Description                 | Type    | Examples                 |
| ------- | --------------------------- | ------- | ------------------------ |
| y       | Year                        | Integer | `2001, 2005, 2020`       |
| yyyy    | 4-digits year               | String  | `"2001", "2005", "2020"` |
| M       | Month of the year (1 based) | Integer | `1, 5, 12`               |
| MM      | 2-digits month              | String  | `"01", "05", "12"`       |
| d       | Day of the month            | Integer | `1, 15, 30`              |
| dd      | 2-digits day of the month   | String  | `"01", "15", "30"`       |
| w       | Week number                 | Integer | `1, 12, 51`              |
| Q       | Quarter                     | Integer | `1, 2, 3, 4`             |
| QQQ     | Quarter prefixed with Q     | String  | `"Q1", "Q2", "Q3", "Q4"` |
| H       | Hour of day (0-23)          | Integer | `0, 12, 23`              |
| HH      | 2-digits hour of day        | String  | `"00", "12", "23"`       |
| m       | Minute of hour              | Integer | `0, 30, 59`              |
| mm      | 2-digits minute of hour     | String  | `"00", "30", "59"`       |
| s       | Second of minute            | Integer | `0, 5, 55`               |
| ss      | 2-digits second of minute   | String  | `"00", "05", "55"`       |

* **Parameters:**
  * **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str)) – The name of the hierarchy to create.
  * **column** ([*Column*](./atoti.column#atoti.Column)) – The column to create the hierarchy from.
    Its [`data_type`](./atoti.Column.data_type#atoti.Column.data_type) must be `LocalDate`, `LocalDateTime`, or `ZonedDateTime`, and it must belong to an in-memory table, not an [`external one`](./atoti.Session.add_external_table#atoti.Session.add_external_table).
  * **levels** ([*Mapping*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Mapping) *\[*[*str*](https://docs.python.org/3/library/stdtypes.html#str) *,* [*str*](https://docs.python.org/3/library/stdtypes.html#str) *]*) – The mapping from the names of the levels to the patterns from which they will be created.
* **Return type:**
  None

### Example

```pycon theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
>>> from datetime import date
>>> df = pd.DataFrame(
...     columns=["Date", "Quantity"],
...     data=[
...         (date(2020, 1, 10), 150.0),
...         (date(2020, 1, 20), 240.0),
...         (date(2019, 3, 17), 270.0),
...         (date(2019, 12, 12), 200.0),
...     ],
... )
>>> table = session.read_pandas(df, keys={"Date"}, table_name="Example")
>>> cube = session.create_cube(table)
>>> l, m = cube.levels, cube.measures
>>> cube.create_date_hierarchy("Date parts", column=table["Date"])
>>> cube.query(
...     m["Quantity.SUM"],
...     include_totals=True,
...     levels=[l["Year"], l["Month"], l["Day"]],
... )
                Quantity.SUM
Year  Month Day
Total                 860.00
2019                  470.00
      3               270.00
            17        270.00
      12              200.00
            12        200.00
2020                  390.00
      1               390.00
            10        150.00
            20        240.00
```

The full date can also be added back as the last level of the hierarchy:

```pycon theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
>>> h = cube.hierarchies
>>> h["Date parts"] = {**h["Date parts"], "Date": table["Date"]}
>>> cube.query(
...     m["Quantity.SUM"],
...     include_totals=True,
...     levels=[l["Date parts", "Date"]],
... )
                           Quantity.SUM
Year  Month Day Date
Total                            860.00
2019                             470.00
      3                          270.00
            17                   270.00
                2019-03-17       270.00
      12                         200.00
            12                   200.00
                2019-12-12       200.00
2020                             390.00
      1                          390.00
            10                   150.00
                2020-01-10       150.00
            20                   240.00
                2020-01-20       240.00
```

Data inserted into the table after the hierarchy creation will be automatically hierarchized:

```pycon theme={"languages":{"custom":["/engine/python-sdk/0.9/languages/pycon.tmLanguage.json"]}}
>>> table += (date(2021, 8, 30), 180.0)
>>> cube.query(
...     m["Quantity.SUM"],
...     include_totals=True,
...     levels=[l["Date parts", "Date"]],
...     filter=l["Year"] == "2021",
... )
                           Quantity.SUM
Year  Month Day Date
Total                            180.00
2021                             180.00
      8                          180.00
            30                   180.00
                2021-08-30       180.00
```