Return the dense rank of the current row (used for window functions).
The dense rank is the rank of the current row without gaps.
Examples:
| >>> import daft
>>> from daft.window import Window
>>> from daft.functions import dense_rank
>>> df = daft.from_pydict(
... {"category": ["A", "A", "A", "A", "B", "B", "B", "B"], "value": [1, 3, 3, 7, 7, 7, 4, 4]}
... )
>>>
>>> window = Window().partition_by("category").order_by("value", desc=True)
>>> df = df.with_column("dense_rank", dense_rank().over(window))
>>> df = df.sort("category")
>>> df.show()
|
╭──────────┬───────┬────────────╮
│ category ┆ value ┆ dense_rank │
│ --- ┆ --- ┆ --- │
│ String ┆ Int64 ┆ UInt64 │
╞══════════╪═══════╪════════════╡
│ A ┆ 7 ┆ 1 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ A ┆ 3 ┆ 2 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ A ┆ 3 ┆ 2 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ A ┆ 1 ┆ 3 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 7 ┆ 1 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 7 ┆ 1 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 4 ┆ 2 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 4 ┆ 2 │
╰──────────┴───────┴────────────╯
(Showing first 8 rows)
Returns:
| Name | Type | Description |
Expression | Expression | An expression that returns the dense rank of the current row. |
Source code in daft/functions/window.py
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149 | def dense_rank() -> Expression:
"""Return the dense rank of the current row (used for window functions).
The dense rank is the rank of the current row without gaps.
Examples:
>>> import daft
>>> from daft.window import Window
>>> from daft.functions import dense_rank
>>> df = daft.from_pydict(
... {"category": ["A", "A", "A", "A", "B", "B", "B", "B"], "value": [1, 3, 3, 7, 7, 7, 4, 4]}
... )
>>>
>>> window = Window().partition_by("category").order_by("value", desc=True)
>>> df = df.with_column("dense_rank", dense_rank().over(window))
>>> df = df.sort("category")
>>> df.show()
╭──────────┬───────┬────────────╮
│ category ┆ value ┆ dense_rank │
│ --- ┆ --- ┆ --- │
│ String ┆ Int64 ┆ UInt64 │
╞══════════╪═══════╪════════════╡
│ A ┆ 7 ┆ 1 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ A ┆ 3 ┆ 2 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ A ┆ 3 ┆ 2 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ A ┆ 1 ┆ 3 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 7 ┆ 1 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 7 ┆ 1 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 4 ┆ 2 │
├╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┤
│ B ┆ 4 ┆ 2 │
╰──────────┴───────┴────────────╯
<BLANKLINE>
(Showing first 8 rows)
Returns:
Expression: An expression that returns the dense rank of the current row.
"""
return Expression._from_pyexpr(native.dense_rank())
|