Eval  type: eval

class lumen.transforms.base.Eval(*, expr, controls, name)

Applies an eval assignment expression to a DataFrame. The expression can reference columns on the original table by referencing table.<column> and must assign to a variable that will become a new column in the DataFrame, e.g. to divide a value column by one thousand and assign the result to a new column called kilo_value you can write an expr like:

kilo_value = table.value / 1000

See pandas.eval for more information.

---

Parameters

expr

type: str
default: ''
The expression to apply to the table.

---

Methods

Eval.apply(table: DataFrame) → DataFrame

Given a table transform it in some way and return it.

Parameters:

table (DataFrame) – The queried table as a DataFrame.

Returns:

A DataFrame containing the transformed data.

Return type:

DataFrame

Eval.to_spec(context: Dict[str, Any] | None = None) → Dict[str, Any]

Exports the full specification to reconstruct this component.

Return type:

Resolved and instantiated Component object