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  * __
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  * polars.LazyF... 

#  polars.LazyFrame.with_row_count  #

LazyFrame.  with_row_count  (  _ name  :  [ str
](https://docs.python.org/3/library/stdtypes.html#str "\(in Python v3.12\)") =
'row_nr'  _ , _ offset  :  [ int
](https://docs.python.org/3/library/functions.html#int "\(in Python v3.12\)")
=  0  _ )  →  Self  [ [source]  ](https://github.com/pola-
rs/polars/blob/main/py-polars/polars/lazyframe/frame.py#L4811-L4856) #

    

Add a column at index 0 that counts the rows.

Deprecated since version 0.20.4:  Use [ ` with_row_index()  `
](polars.LazyFrame.with_row_index.html#polars.LazyFrame.with_row_index
"polars.LazyFrame.with_row_index") instead. Note that the default column name
has changed from ‘row_nr’ to ‘index’.

Parameters  :

    

**name**

    

Name of the column to add.

**offset**

    

Start the row count at this offset.

Warning

This can have a negative effect on query performance. This may, for instance,
block predicate pushdown optimization.

Examples

    
    
    >>> lf = pl.LazyFrame(
    ...     {
    ...         "a": [1, 3, 5],
    ...         "b": [2, 4, 6],
    ...     }
    ... )
    >>> lf.with_row_count().collect()  
    shape: (3, 3)
    ┌────────┬─────┬─────┐
    │ row_nr ┆ a