Lazy loading#

For large meshes (gigabytes of binary data), pass lazy=True. polyxios memory-maps the file and only loads the pages you actually touch - the rest stays on disk until needed.

# File is opened but data is not loaded into RAM yet
mesh = px.read("huge_brain.vtk", lazy=True)

# Only the vertices are pulled from disk here
first_vertex = mesh.vertices[0]

# Element connectivity is still on disk until you access it

Lazy loading is supported for binary .vtk, .ply, .stl and .meshb files. ASCII formats load eagerly (the whole file must be parsed to extract values). Binary STL lazy mode skips vertex deduplication - vertices are returned as-is (3 per triangle), avoiding the extra pass over the data.