Documentation

Type-check the columns of your Polars frames

Astrolabe is a mypy plugin. It checks the column names and the data types of Polars frames and expressions before the code runs.

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Start here

Set up the checker

Install the plugin and type your first frame.

• Install and set up
• Quickstart

Tutorial

Follow one pipeline

Load, transform and check a pipeline over trades data.

• Load data with a schema
• Write a function that accepts other columns

Guides

Learn the types

Schemas, operations, open frames and expression types.

• Schemas
• Open frames
• Declare expression types

Reference

Look up a detail

Every operation, error code and setting.

• Error codes
• Configuration
• Operations

Requirements

Set up in one command

Astrolabe needs Python 3.12 or later, mypy 1.13 or later and Polars 1.43.2. Install the package, then runastrolabe init in your project.

Install and set up

pipeline.pymypy: 1 error

1class Trades(Columns):

2 symbol: pl.String

3 price: pl.Float64

4 quantity: pl.Int64

5

6

7trades: TypedDataFrame[Trades]

8trades.select("venue")

↑error: Unknown column "venue" [unknown-column]