Creating reusable expressions

Now that you can transform columns, you want to understand which artists have a dedicated fanbase by calculating streams per listener. Rather than rewriting this formula each time, store the calculation as a Polars expression variable that you can reuse across multiple DataFrames.

polars is loaded as pl. The DataFrame spotify is available with album streaming data.

Diese Übung ist Teil des Kurses

Data Transformation with Polars

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Anleitung zur Übung

Create an expression that divides streams by monthly_listeners.
Apply the expression variable and sort by streams_per_listener in descending order.

Interaktive Übung

Vervollständige den Beispielcode, um diese Übung erfolgreich abzuschließen.

# Create a reusable expression for streams per listener
streams_per_listener_expr = (
    (pl.col("____") / pl.col("____"))
    .alias("streams_per_listener")
)

# Apply the expression and sort by streams_per_listener
result = spotify.with_columns(____).sort(
    "streams_per_listener", descending=____
)

print(result.head())

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