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  * [ __ ](../../../index.html)
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  * __
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  * polars.LazyF... 

#  polars.LazyFrame.cast  #

LazyFrame.  cast  (

     _ dtypes  :  Mapping  [  ColumnNameOrSelector  |  PolarsDataType  ,  PolarsDataType  ]  |  PolarsDataType  _ , 
     _ *  _ , 
     _ strict  :  [ bool  ](https://docs.python.org/3/library/functions.html#bool "\(in Python v3.12\)") =  True  _ , 
)  →  Self  [ [source]  ](https://github.com/pola-rs/polars/blob/main/py-
polars/polars/lazyframe/frame.py#L2508-L2607) #

    

Cast LazyFrame column(s) to the specified dtype(s).

Parameters  :

    

**dtypes**

    

Mapping of column names (or selector) to dtypes, or a single dtype to which
all columns will be cast.

**strict**

    

Throw an error if a cast could not be done (for instance, due to an overflow).

Examples

    
    
    >>> from datetime import date
    >>> lf = pl.LazyFrame(
    ...     {
    ...         "foo": [1, 2, 3],
    ...         "bar": [6.0, 7.0, 8.0],
    ...         "ham": [date(2020, 1, 2), date(2021, 3, 4), date(2022, 5, 6)],
    ...     }
    ... )
    

Cast specific frame columns to the specified dtypes:

    
    
    >>> lf.cast({"foo": pl.Float32, "bar": pl.UInt8}).collect()
    shape: (3, 3)
    ┌─────┬─────┬────────────┐
    │ foo ┆ bar ┆ ham