3b1b/manim · error · Exception

All submobjects must be of type PMobject

Error message

All submobjects must be of type PMobject

What it means

Raised by PGroup.__init__ (point_cloud_mobject.py:104) when any of the positional arguments passed to PGroup is not an instance of PMobject. PGroup is the point-cloud analogue of VGroup and enforces that all its children share the PMobject data model (points + rgba arrays).

Source

Thrown at manimlib/mobject/types/point_cloud_mobject.py:104

            sm.data.array for sm in self.get_family()
        ]))
        return self

    def point_from_proportion(self, alpha: float) -> np.ndarray:
        index = alpha * (self.get_num_points() - 1)
        return self.get_points()[int(index)]

    def pointwise_become_partial(self, pmobject: PMobject, a: float, b: float) -> Self:
        lower_index = int(a * pmobject.get_num_points())
        upper_index = int(b * pmobject.get_num_points())
        self.set_data(pmobject.data[lower_index:upper_index])
        return self


class PGroup(PMobject):
    def __init__(self, *pmobs: PMobject, **kwargs):
        if not all([isinstance(m, PMobject) for m in pmobs]):
            raise Exception("All submobjects must be of type PMobject")
        super().__init__(**kwargs)
        self.add(*pmobs)

View on GitHub (pinned to dee01804d4)

Solutions

1. Use Points(...)/other PMobject instances inside PGroup instead of VMobjects like Dot or Circle
2. If you actually wanted a group of dots, use VGroup(Dot(...)) (vectorized) rather than PGroup
3. Validate with isinstance(m, PMobject) on each element before constructing

Example fix

# before
pg = PGroup(Dot(), Dot())  # Dot is a VMobject -> raises

# after
pg = PGroup(Points([[-1, 0, 0], [1, 0, 0]]))

assert all(isinstance(m, PMobject) for m in pmobs), 'PGroup needs PMobjects only'
pg = PGroup(*pmobs)

from manimlib.mobject.types.point_cloud_mobject import PMobject

def is_pmobject(m) -> bool:
    return isinstance(m, PMobject)

When it happens

Trigger: PGroup(Dot(), Points()) raises because Dot is a VMobject, not a PMobject; PGroup(VGroup()) and PGroup(Mobject()) also raise. Only point-cloud mobjects such as Points / PMobject subclasses are accepted.

Common situations: Assuming the familiar VGroup API accepts anything and writing PGroup(Dot(...)); migrating scenes between vectorized and point-cloud styles while reusing container code.

Related errors

• All submobjects must be of type VMobject
• Only VMobjects can be passed into VGroup
• Invalid color type
• Unsupported: {path_verb}
• At least 2 mobjects needed for Union.

AI-assisted analysis of 3b1b/manim@dee01804d4 (2026-08-14). Data as JSON: /api/errors/232259782e774e55. Report an issue: GitHub.