---
pretty_name: jax-fli MAP and chain outputs
license: mit
language:
- en
tags:
- cosmology
- weak-lensing
- field-level-inference
- mcmc
- healpix
- jax
size_categories:
- n<1K
---

# jax-fli MAP and chain outputs

Maximum a posteriori reconstructions and MCMC chains of the [`jax-fli`](https://github.com/DifferentiableUniverseInitiative/jax-fli) forward model: 2LPT on a spherical lightcone of capped equal-volume shells, Born convergence, and a pixel likelihood on two tomographic κ maps. The notebooks in [`docs/3-sampling-and-inference`](https://github.com/DifferentiableUniverseInitiative/jax-fli/tree/main/docs/3-sampling-and-inference) produced the runs, and experiment [`13-map-lpt2-mass-mapping`](https://github.com/DifferentiableUniverseInitiative/jax-fli/tree/main/docs/5-experiments/13-map-lpt2-mass-mapping) draws its figures from the MAP runs. The accuracy experiments are in [`ASKabalan/jax-fli-experiments`](https://huggingface.co/datasets/ASKabalan/jax-fli-experiments), and the scaling benchmarks in [`ASKabalan/jax-fli-scaling`](https://huggingface.co/datasets/ASKabalan/jax-fli-scaling).

| folder | content | produced by |
|---|---|---|
| `13-LPT-MassMapping/mesh_416_DES/` | MAP reconstruction of the initial conditions at 416³ from the κ maps of DES Y3 source bins 2 and 3 (1.48 galaxies/arcmin² per bin, σ_e = 0.26, 300 Adam steps) | notebook `14-LPT-MassMapping.ipynb`, Part I |
| `13-LPT-MassMapping/mesh_416_EUCLID/` | the same reconstruction at Euclid IST:F noise (7.5 galaxies/arcmin² per bin, σ_e = 0.21 per component, 400 Adam steps) | notebook `14-LPT-MassMapping.ipynb`, Part II |
| `14-LPT-Sampling/` | MCLMC chain over (Ω_c, σ₈) and the 128³ initial conditions (`chain/`), the cosmology chain with the initial conditions held fixed (`chain_fixed_ic/`, `chain_cosmology.npz`), the truth (`truth/`), the lensing-kernel projections of the samples (`projected_ic/`), summaries and figures | notebooks `16-LPT-FieldLevel-IC.ipynb` and `17-LPT-FieldLevel-Cosmology.ipynb` |
| `15-inference-cosmogrid/truth/input_cg.parquet` | a CosmoGrid density field (832³ in a 900 Mpc/h box), the truth of the retired inference experiment `14-inference-cosmogrid-shear` | — |

Each MAP run holds the static truth (`true_ic`, `truth_kappa`, `observed_kappa`, `truth_density_lightcone`, `lattice_density_lightcone`), eleven log-spaced frames of the optimisation in each `*_evolution/` folder (IC, density lightcone, κ, and the coherence and transfer function of the IC and of κ against the truth), and `metrics.json`, `summary.json` and `loss_history.npz`. Every parquet is a serialised `jax_fli.io.Catalog`. The `chain/sampling_state/` and `chain_fixed_ic/warmup_state/` folders are Orbax checkpoints that resume the chains.

```python
from pathlib import Path

from huggingface_hub import snapshot_download
from jax_fli.io import Catalog

REPO = "ASKabalan/jax-fli-sampling"
root = Path(snapshot_download(REPO, repo_type="dataset", allow_patterns=["13-LPT-MassMapping/mesh_416_DES/*.parquet"]))
truth_kappa = Catalog.from_parquet(str(root / "13-LPT-MassMapping/mesh_416_DES/truth_kappa.parquet")).field[0]
```