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  * polars.LazyF... 

#  polars.LazyFrame.approx_n_unique  #

LazyFrame.  approx_n_unique  (  )  →  Self  [ [source]
](https://github.com/pola-rs/polars/blob/main/py-
polars/polars/lazyframe/frame.py#L4702-L4732) #

    

Approximate count of unique values.

Deprecated since version 0.20.11:  Use ` select(pl.all().approx_n_unique())  `
instead.

This is done using the HyperLogLog++ algorithm for cardinality estimation.

Examples

    
    
    >>> lf = pl.LazyFrame(
    ...     {
    ...         "a": [1, 2, 3, 4],
    ...         "b": [1, 2, 1, 1],
    ...     }
    ... )
    >>> lf.approx_n_unique().collect()  
    shape: (1, 2)
    ┌─────┬─────┐
    │ a   ┆ b   │
    │ --- ┆ --- │
    │ u32 ┆ u32 │
    ╞═════╪═════╡
    │ 4   ┆ 2   │
    └─────┴─────┘
    

[ __ previous  Manipulation/selection  ](../modify_select.html "previous
page") [ next  polars.LazyFrame.bottom_k  __ ](polars.LazyFrame.bottom_k.html
"next page")

__ On this page

  * ` LazyFrame.approx_n_unique()  `

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