api/polars.exceptions.DuplicateError.html)
    * [ polars.exceptions.InvalidOperationError ](../../api/polars.exceptions.InvalidOperationError.html)
    * [ polars.exceptions.NoDataError ](../../api/polars.exceptions.NoDataError.html)
    * [ polars.exceptions.NoRowsReturnedError ](../../api/polars.exceptions.NoRowsReturnedError.html)
    * [ polars.exceptions.PolarsError ](../../api/polars.exceptions.PolarsError.html)
    * [ polars.exceptions.PolarsPanicError ](../../api/polars.exceptions.PolarsPanicError.html)
    * [ polars.exceptions.RowsError ](../../api/polars.exceptions.RowsError.html)
    * [ polars.exceptions.SchemaError ](../../api/polars.exceptions.SchemaError.html)
    * [ polars.exceptions.SchemaFieldNotFoundError ](../../api/polars.exceptions.SchemaFieldNotFoundError.html)
    * [ polars.exceptions.ShapeError ](../../api/polars.exceptions.ShapeError.html)
    * [ polars.exceptions.StructFieldNotFoundError ](../../api/polars.exceptions.StructFieldNotFoundError.html)
    * [ polars.exceptions.TooManyRowsReturnedError ](../../api/polars.exceptions.TooManyRowsReturnedError.html)

  * [ Testing ](../../testing.html) __
    * [ polars.testing.assert_frame_equal ](../../api/polars.testing.assert_frame_equal.html)
    * [ polars.testing.assert_frame_not_equal ](../../api/polars.testing.assert_frame_not_equal.html)
    * [ polars.testing.assert_series_equal ](../../api/polars.testing.assert_series_equal.html)
    * [ polars.testing.assert_series_not_equal ](../../api/polars.testing.assert_series_not_equal.html)
    * [ polars.testing.parametric.dataframes ](../../api/polars.testing.parametric.dataframes.html)
    * [ polars.testing.parametric.series ](../../api/polars.testing.parametric.series.html)
    * [ polars.testing.parametric.column ](../../api/polars.testing.parametric.column.html)
    * [ polars.testing.parametric.columns ](../../api/polars.testing.parametric.columns.html)
    * [ polars.testing.parametric.create_list_strategy ](../../api/polars.testing.parametric.create_list_strategy.html)
    * [ polars.testing.parametric.load_profile ](../../api/polars.testing.parametric.load_profile.html)
    * [ polars.testing.parametric.set_profile ](../../api/polars.testing.parametric.set_profile.html)

  * [ Metadata ](../../metadata.html) __
    * [ polars.build_info ](../../api/polars.build_info.html)
    * [ polars.get_index_type ](../../api/polars.get_index_type.html)
    * [ polars.show_versions ](../../api/polars.show_versions.html)
    * [ polars.thread_pool_size ](../../api/polars.thread_pool_size.html)
    * [ polars.threadpool_size ](../../api/polars.threadpool_size.html)

  * [ __ ](../../../index.html)
  * [ Python API reference ](../../index.html)
  * __
  * [ Aggregation ](../aggregation.html)
  * polars.LazyF... 

#  polars.LazyFrame.count  #

LazyFrame.  count  (  )  →  Self  [ [source]  ](https://github.com/pola-
rs/polars/blob/main/py-polars/polars/lazyframe/frame.py#L6119-L6138) #

    

Return the number of non-null elements for each column.

Examples

    
    
    >>> lf = pl.LazyFrame(
    ...     {"a": [1, 2, 3, 4], "b": [1, 2, 1, None], "c": [None, None, None, None]}
    ... )
    >>> lf.count().collect()
    shape: (1, 3)
    ┌─────┬─────┬─────┐
    │ a   ┆ b   ┆ c   │
    │ --- ┆ --- ┆ --- │
    │ u32 ┆ u32 ┆ u32 │
    ╞═════╪═════╪═════╡
    │ 4   ┆ 3   ┆ 0   │
    └─────┴─────┴─────┘
    

[ __ previous  Aggregation  ](../aggregation.html "previous page") [ next
polars.LazyFrame.max  __ ](polars.LazyFrame.max.html "next page")

__ On this page

  * ` LazyFrame.count()  `

© Copyright 2020, Ritchie Vink.  

Created using [ Sphinx ](https://www.sphinx-doc.org/) 7.2.4.  

Built with the [ PyData Sphinx Theme ](https://pydata-sphinx-
theme.readthedocs.io/en/stable/index.html) 0.14.1.