PRFclass

A Python interface for working with population receptive field (pRF) results: loading them from disk, masking them down to the voxels/vertices you care about, computing derived measures, and plotting them — in the visual field, on the cortical surface, or on a flatmap.

Two classes do the work:

class	scope
PRF	one subject / session / task / run
PRFgroup	many of them at once, held in a pandas DataFrame

PRFgroup mirrors the PRF interface, so the same masking calls and the same parameter names work whether you are looking at one dataset or a whole study.

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Where the data comes from

PRFclass is built to read the output of prfprepare → prfanalyze. It works with GEM-pRF (method="gem") and with vistasoft (method="vista"), and it also reads mrVista sessions, SAMSrf results, plain HDF5 estimates and loose files through the other constructors.

The expected layout is the standard BIDS derivatives tree:

<baseP>/<study>/
└── derivatives
    ├── prfprepare
    │   └── analysis-01
    └── prfanalyze-gem          # or prfanalyze-vista, …
        └── analysis-01
            └── sub-<subject>/ses-<session>/
                └── sub-<subject>_ses-<session>_task-<task>_run-<run>_hemi-<L|R>_estimates.h5

A <study>/BIDS/derivatives layout is picked up automatically as a fallback. The ROI masks and atlases written by prfprepare are read through the roipack submodule, which is what makes maskROI("V1", "benson") and the ROI borders in the surface plots work.

Scope

This package was developed at the Medical University of Vienna, around our data organisation and our file server — that is where the default baseP and a few path conventions come from. It is not tied to it, though: if your data went through prfprepare, PRFclass should work for you by passing your own baseP and study. The Vienna-specific parts are defaults, not requirements.

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Install

Clone the repository with its submodule into a directory that is on your Python path:

git clone --recursive https://github.com/dlinhardt/PRFclass

If you already have a clone without roipack:

git submodule update --init

Then import it as a package from the parent directory:

import sys
sys.path.append("/path/to/where/you/cloned")   # the folder *containing* PRFclass

from PRFclass import PRF, PRFgroup

Required libraries

Install these with conda or pip, whichever your environment uses:

Core — needed to import the package at all: numpy, scipy, matplotlib, pandas, nibabel, nilearn, h5py, pillow, tqdm, reportlab, pyvista, vtk

Flatmaps only — plot_toFlatmap() and prepare_flatmap_surface(): pycortex, svglib

Optional — neuropythy (some atlas paths and SAMSrf data)

Surfaces are rendered with PyVista/VTK, flatmaps with pycortex. mayavi and pysurfer are no longer used — do not install them. PyQt5 next to PyQt6 in one environment produces the QT_ROOT_LEVEL_POOL is implemented in both libQt5Core and libQt6Core warning, and mayavi's off-screen renderer needs OSMesa, so it does not work on macOS at all.

Headless Linux (cluster) needs an off-screen VTK build:

pip uninstall vtk
pip install --extra-index-url https://wheels.vtk.org vtk-osmesa   # CPU
pip install --extra-index-url https://wheels.vtk.org vtk-egl      # GPU

or run your script under xvfb-run -a python your_script.py. Note that pv.start_xvfb() was removed in pyvista 0.48 — do not call it. On macOS nothing extra is needed.

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Quick start

A fuller, commented walkthrough lives in PRFclass_example.py.

One dataset

from PRFclass import PRF

ana = PRF.from_docker(
    baseP="/path/to/data",
    study="my_study",
    subject="001", session="001", task="bars", run="01",
    method="gem",        # or "vista"
    analysis="01",
    hemi="",             # "" = both hemispheres, or "L" / "R"
)

ana.list_atlases_and_rois()   # see what atlases and ROIs are available

ana.maskVarExp(0.1)           # keep voxels with R² > 0.1
ana.maskROI("V1", "benson")   # …inside V1  (a list of ROIs also works)

ana.x, ana.y, ana.ecc, ana.pol, ana.sigma, ana.varexp   # masked parameters

A whole study

from PRFclass import PRFgroup

anas = PRFgroup.from_docker(
    baseP="/path/to/data",
    study="my_study",
    subjects=".*", sessions=".*", tasks=".*", runs=".*",   # regex selection
    method="gem",
    prfanalyze="01",
)

anas.maskVarExp(0.1)
anas.maskROI("V1", "benson")

anas.data      # DataFrame: subject, session, task, run, prf
anas.ecc       # all subjects concatenated
anas.sub_ecc   # dict, one entry per subject

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Three things worth knowing

Masking is a stack, not a filter. Nothing is ever thrown away. Each maskX() call defines one mask; .mask is the combination of all active ones. Every mask can be switched off again without reloading:

ana.doVarExpMsk = False   # also doROIMsk, doEccMsk, doSigMsk, doBetaMsk, doManualMsk

A trailing 0 means unmasked. ana.x gives you the masked voxels, ana.x0 gives you all of them. This holds for every parameter — ecc/ecc0, pol/pol0, varexp/varexp0, voxelTC/voxelTC0, and so on.

A group is a DataFrame of PRF objects. anas.data["prf"] holds the real PRF instances, so anything you can do to one you can do to all of them. anas.query("subject == '001'") returns a filtered PRFgroup, and anas.iterate("plot_covMap", save=True) runs a method across the group.

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What you can do with it

Load	prfanalyze results (gem, vistasoft) via Docker/BIDS derivatives, mrVista sessions, SAMSrf, HDF5, or individual files
Mask	by ROI and atlas, variance explained, eccentricity, pRF size, beta amplitude, a dartboard segmentation, or an interactive hand-drawn mask
Parameters	x, y, ecc, pol, sigma, beta, varexp — masked or unmasked, per dataset or pooled across a group
Time courses	measured BOLD (voxelTC), the fitted model signal (modelsignal, modelpred), and r2_against() to score a model against any run
Stimulus & motion	load the stimulus apertures, eye-tracker jitter, and realignment/framewise-displacement parameters
Analyse	visual field coverage, KDE-difference maps and central scotoma borders, pRF profiles
Plot	coverage maps, multi-subject coverage PDFs, 3D cortical surfaces, pycortex flatmaps
Export	write parameters and masks back out as NIfTI or GIFTI (save_results)

The gem results also expose the fitting grid (searchSpace) and stimulus metadata (stimulusInfo) — useful, for example, to mask out fits that ran into the edge of the search space.

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Visualisation

Coverage maps

ana.plot_covMap(method="max", save=True)
anas.plot_coverage_summary_pdf()   # one PDF for the whole group

Cortical surfaces

ana.plot_toSurface(param="pol", hemi="both", surface="inflated",
                   save=True, headless=True, output_format="pdf")

Any native FreeSurfer surface works (pial, white, inflated, sphere, …), plus a few convenience names (midthickness, very_inflated, grey, cortex). ROI borders, colormaps and colorbars are configurable; colorbars are written to a separate file by default so the brain image stays clean.

Camera positions are stored per subject, hemisphere, area and surface under derivatives/prfresult/positioning/. Run once with headless=False to pick a view interactively; in headless mode a missing position falls back to a default view and is not saved, so you can still set it later.

Flatmaps

ana.plot_toFlatmap(param="pol", showBordersAtlas="benson", showBordersArea="V1",
                   save=True)

Same parameters, masking, colormaps and colorbars as plot_toSurface. Subjects are imported into pycortex's filestore automatically on first use, from surfaces only — so volume-based pycortex features (cortex.Volume, transforms) are not available for auto-imported subjects; run cortex.freesurfer.import_subj yourself if you need them.

Flatmaps need a flattened surface. fsaverage ships one; for individual subjects:

ana.prepare_flatmap_surface()           # runs mris_flatten, hours per hemisphere
ana.prepare_flatmap_surface(run=False)  # only print the commands, e.g. for a cluster

This requires an existing ?h.cortex.patch.3d cut — where to cut is a manual decision and is not automated.

Citing PRFclass

If PRFclass contributed to work you publish, please cite it. GitHub's Cite this repository button (top right, from CITATION.cff) gives you ready-made APA and BibTeX entries:

@software{prfclass,
  author  = {Linhardt, David},
  title   = {PRFclass: a Python interface for population receptive field results},
  version = {2.0},
  url     = {https://github.com/dlinhardt/PRFclass},
}

Please also cite prfprepare and, if you used it, GEM-pRF.

License

MIT — see LICENSE. Do whatever you like with it; just keep the copyright notice, and cite the repository if you use it in published work.