Open VMEC wout*.nc equilibrium files directly in VS Code and explore them with interactive
Plotly figures — a summary dashboard, 1D profiles, 2D cross-sections, 3D geometry, and field
lines.
Requires a Python backend. This extension is the UI only; all numerics run in Python
(JAX). You must install the vmecdash package into a Python interpreter and select that
interpreter in VS Code. See Requirements below — without it a file will open but nothing renders.
Features
Custom editor for **/wout*.nc — just open the file.
Views: Summary dashboard, 1D profiles, 2D cross-section (R–Z carpet / flux surface),
3D geometry, and field lines.
Per-view controls that adapt automatically (dropdowns, sliders with live value readouts,
toggles), driven by a schema the backend ships — new physical quantities appear without a
UI change.
Light/dark aware; bundled Plotly.js (no CDN); works locally and over Remote-SSH.
Requirements
Python ≥ 3.10 with the backend installed:
pip install vmecdash
JAX is pulled in automatically; the CPU build works out of the box.
Select the interpreter with Command Palette → “VMECdash: Select Python Interpreter”.
This opens the Microsoft Python extension's native Python: Select Interpreter picker.
VMECdash resolves the backend interpreter in this order:
the vmecdash.pythonPath setting, as an advanced manual override, or
the VMECDASH_PYTHON environment variable (handy for Remote-SSH / CI / terminal
launches), or
the interpreter selected by the Microsoft Python extension, or
python3 / python on your PATH.
The chosen interpreter must have vmecdash installed. If it doesn't, the extension tells you
which interpreter it used and offers a Select Python Interpreter button — it won't fail silently.
Run “VMECdash: Check Backend” from the Command Palette to verify (vmecdash + jax
versions).
On Remote-SSH, install vmecdash in the remote interpreter — the backend runs on the
remote host, so no localhost server or file upload is needed.
Usage
Open any wout*.nc file (or run “VMECdash: Open Preview”).
Pick a view on the left; adjust its controls on the right.
“VMECdash: Export Report” writes a text summary of scalars and metadata.
Settings
Setting
Description
vmecdash.pythonPath
Advanced override for the Python executable that runs python -m vmecdash.vscode_backend --stdio.
vmecdash.backendArgs
Extra arguments passed to the backend.
Troubleshooting
If a wout file opens but no figure appears, the selected interpreter is almost certainly
missing vmecdash or jax. Run “VMECdash: Check Backend” for a diagnostic, then
pip install vmecdash into that interpreter and reload.
