build123d/docs/algebra_performance.rst
2025-09-09 23:21:05 -04:00

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.. _algebra_performance:
Performance considerations in algebra mode
===============================================
Creating lots of Shapes in a loop means for every step ``fuse`` and ``clean`` will be called.
In an example like the below, both functions get slower and slower the more objects are
already fused. Overall it takes on an M1 Mac 4.76 sec.
.. code-block:: build123d
diam = 80
holes = Sketch()
r = Rectangle(2, 2)
for loc in GridLocations(4, 4, 20, 20):
if loc.position.X**2 + loc.position.Y**2 < (diam / 2 - 1.8) ** 2:
holes += loc * r
c = Circle(diam / 2) - holes
One way to avoid it is to use lazy evaluation for the algebra operations. Just collect all objects and
then call ``fuse`` (``+``) once with all objects and ``clean`` once. Overall it takes 0.19 sec.
.. code-block:: build123d
r = Rectangle(2, 2)
holes = [
loc * r
for loc in GridLocations(4, 4, 20, 20).locations
if loc.position.X**2 + loc.position.Y**2 < (diam / 2 - 1.8) ** 2
]
c = Circle(diam / 2) - holes
Another way to leverage the vectorized algebra operations is to add a list comprehension of objects to
an empty ``Part``, ``Sketch`` or ``Curve``:
.. code-block:: build123d
polygons = Sketch() + [
loc * RegularPolygon(radius=5, side_count=5)
for loc in GridLocations(40, 30, 2, 2)
]
This again ensures one single ``fuse`` and ``clean`` call.