Welcome to the OpenCosmo Toolkit Documentation

The OpenCosmo Python Toolkit provides utilities for reading, writing and manipulating data from cosmological simulations produced by the Cosmolgical Physics and Advanced Computing (CPAC) group at Argonne National Laboratory. It can be used to work with smaller quantities data retrieved with the CosmoExplorer, as well as the much larget datasets these queries draw from. The OpenCosmo toolkit integrates with standard tools such as AstroPy, and allows you to manipulate data in a fully-consistent cosmological context.

Getting Started

• Installation
• First Steps

General Usage

• Main Transformations API
  • Unit Conventions
  • Adding Columns
  • Filtering
  • Selecting Columns
  • Taking Rows
  • Sorting
  • Spatial Querying
  • Iterating Over Rows
  • Evaluating Complex Expressions
• Working with Columns
  • Querying Based on Column Values
  • Querying In Collections
  • Adding Custom Columns
• Working with Collections
  • Types of Collections
  • Lightcones
  • Structure Collections
  • Transformations on Structure Collections
  • Healpix Maps
  • Simulation Collections
• Working with Units
  • Converting Between Unit Conventions
  • Converting Columns to an Equivalent Unit
  • Single-Column Conversions
  • Conversion Precedence
  • Structure Collection Conversions
  • Clearing Conversions
• Reading and Writing Data
  • Options for Reading Data
  • Writing Data
  • Other Formats

Advanced Usage

• Evaluating Complex Expressions on Datasets and Collections
• Working with MPI
• Performance Tips

Analysis and Visualization

• Analyzing Particle Data with yt
• Simulating X-ray Emission with pyXSIM
• Visualizing Halos

API Reference

• Reading/Writing
• Dataset
• Collections
• Columns
• Parameters and the OpenCosmoHeader
• Regions
• Analysis

Changelog

• opencosmo 1.3.3 (2026-06-03)
• opencosmo 1.3.2 (2026-06-03)
• opencosmo 1.3.1 (2026-05-27)
• opencosmo 1.2.5 (2026-04-15)
• opencosmo 1.2.4 (2026-03-27)
• opencosmo 1.2.3 (2026-03-23)
• opencosmo 1.2.2 (2026-03-23)
• opencosmo 1.2.1 (2026-03-23)
• opencosmo 1.2.0 (2026-03-23)
• Opencosmo 1.1.5 (2026-03-11)
• Opencosmo 1.1.4 (2026-02-25)
• opencosmo 1.1.3 (2026-02-18)
• opencosmo 1.1.2 (2026-02-16)
• opencosmo 1.1.1 (2026-02-16)
• opencosmo 1.1.0 (2026-02-10)
• opencosmo 1.0.4 (2026-02-04)
• opencosmo 1.0.3 (2026-01-30)
• opencosmo 1.0.2 (2026-01-28)
• opencosmo 1.0.1 (2026-01-21)
• opencosmo 1.0.0 (2026-01-21)
• opencosmo 0.9.6 (2025-10-20)
• opencosmo 0.9.4 (2025-09-26)
• opencosmo 0.9.3 (2025-09-25)
• opencosmo 0.9.2 (2025-09-25)
• opencosmo 0.9.1 (2025-09-16)
• opencosmo 0.9.0 (2025-09-15)
• opencosmo 0.8.0 (2025-07-22)