Polars 2 cheatsheet

Polars 2: Basics

8 common Polars 2 tasks.

Install Polars

Install the Polars library.

pip install polars

Build a DataFrame from a dictionary of columns.

import polars as pl

df = pl.DataFrame({
    "name": ["Ada", "Grace", "Linus"],
    "age": [36, 45, 28],
    "team": ["a", "b", "a"],
})

Load a CSV into a DataFrame.

df = pl.read_csv("data.csv")

Preview rows, check the schema and summarize numeric columns.

df.head()
df.schema
df.describe()

Choose columns by name or expression.

df.select("name", "age")
df.select(pl.col("age") * 2)

Keep rows that match a condition. Combine conditions with & and |.

df.filter((pl.col("age") > 30) & (pl.col("team") == "a"))

Create new columns from expressions. Existing columns with the same name are replaced.

df.with_columns(
    (pl.col("age") + 1).alias("next_age"),
    pl.col("name").str.to_uppercase().alias("shout"),
)

Sort by one or more columns.

df.sort("age", descending=True)