/api/polars.exceptions.DuplicateError.html)
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  * [ Testing ](../../testing.html) __
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    * [ polars.testing.parametric.set_profile ](../../api/polars.testing.parametric.set_profile.html)

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    * [ polars.threadpool_size ](../../api/polars.threadpool_size.html)

  * [ __ ](../../../index.html)
  * [ Python API reference ](../../index.html)
  * __
  * [ Manipulation/selection ](../modify_select.html)
  * polars.LazyF... 

#  polars.LazyFrame.melt  #

LazyFrame.  melt  (

     _ id_vars  :  ColumnNameOrSelector  |  Sequence  [  ColumnNameOrSelector  ]  |  [ None  ](https://docs.python.org/3/library/constants.html#None "\(in Python v3.12\)") =  None  _ , 
     _ value_vars  :  ColumnNameOrSelector  |  Sequence  [  ColumnNameOrSelector  ]  |  [ None  ](https://docs.python.org/3/library/constants.html#None "\(in Python v3.12\)") =  None  _ , 
     _ variable_name  :  [ str  ](https://docs.python.org/3/library/stdtypes.html#str "\(in Python v3.12\)") |  [ None  ](https://docs.python.org/3/library/constants.html#None "\(in Python v3.12\)") =  None  _ , 
     _ value_name  :  [ str  ](https://docs.python.org/3/library/stdtypes.html#str "\(in Python v3.12\)") |  [ None  ](https://docs.python.org/3/library/constants.html#None "\(in Python v3.12\)") =  None  _ , 
     _ *  _ , 
     _ streamable  :  [ 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#L5555-L5620) #

    

Unpivot a DataFrame from wide to long format.

Optionally leaves identifiers set.

Thi