Polars ROOT

Polars plugin for reading CERN's ROOT file format. Uses Uproot and Awkward Arrays under the hood.

Installation

polars-root supports Python 3.10 and later. To install for use with standard polars, run:

pip install 'polars-root[standard]'

To install for use with polars-u64-idx, run:

pip install 'polars-root[u64-idx]'

Usage

import polars as pl
import polars_root as pr

# Read TTree `tree_name` from a ROOT file into a Polars DataFrame
df = pr.read_root("example.root", "tree_name")

# Read TTree `tree_name` from a ROOT file into a Polars LazyFrame
lf = pr.scan_root("example.root", "tree_name")

# Load TTree `tree_name` from a ROOT file into a LazyFrame, perform some operations, and then sink to parquet
(
    pr.scan_root("example.root", "tree_name")
    .filter(pl.col("some_column") > 0)
    .select(["some_column", "another_column"])
    .sink_parquet("output.parquet")
)

# Also supports opening a ROOT file and jumping straight to a TTree using a colon, as in Uproot:
df = pr.read_root("example.root:tree_name")