cannot import name 'csrc' from 'gsplat'

I referred to the demo_single_object.ipynb script and encountered an error when running the code:
video = render_video(
scene_gs,
r=1,
fov=60,
pitch_deg=15,
yaw_start_deg=-45,
resolution=512,
)["color"].
The error message is as follows:
Traceback (most recent call last):
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/cuda/_backend.py", line 166, in
from gsplat import csrc as _C
ImportError: cannot import name 'csrc' from 'gsplat' (/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/__init__.py)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "/home/work_code/sam3d-objects-main/demo2.py", line 36, in
video = render_video(
^^^^^^^^^^^^^
File "/home/work_code/sam3d-objects-main/notebook/inference.py", line 183, in render_video
return render_utils.render_frames(
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/work_code/sam3d-objects-main/sam3d_objects/model/backbone/tdfy_dit/utils/render_utils.py", line 94, in render_frames
res = renderer.render(sample, extr, intr, colors_overwrite=colors_overwrite)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/work_code/sam3d-objects-main/sam3d_objects/model/backbone/tdfy_dit/renderers/gaussian_render.py", line 298, in render
render_ret = render(
^^^^^^^
File "/home/work_code/sam3d-objects-main/sam3d_objects/model/backbone/tdfy_dit/renderers/gaussian_render.py", line 181, in render
render_colors, render_alphas, meta = rasterization(
^^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/rendering.py", line 409, in rasterization
proj_results = fully_fused_projection(
^^^^^^^^^^^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/cuda/_wrapper.py", line 404, in fully_fused_projection
return _FullyFusedProjectionPacked.apply(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/torch/autograd/function.py", line 575, in apply
return super().apply(*args, **kwargs) # type: ignore[misc]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/cuda/_wrapper.py", line 1606, in forward
camera_model_type = _make_lazy_cuda_obj(
^^^^^^^^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/cuda/_wrapper.py", line 24, in _make_lazy_cuda_obj
from ._backend import _C
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/cuda/_backend.py", line 217, in
_C = load_extension(
^^^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/gsplat/cuda/_backend.py", line 79, in load_extension
compiled = _jit_compile(
^^^^^^^^^^^^^
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/torch/utils/cpp_extension.py", line 1721, in _jit_compile
_write_ninja_file_and_build_library(
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/torch/utils/cpp_extension.py", line 1803, in _write_ninja_file_and_build_library
verify_ninja_availability()
File "/home/anaconda3/envs/sam3d-objects/lib/python3.11/site-packages/torch/utils/cpp_extension.py", line 1852, in verify_ninja_availability
raise RuntimeError("Ninja is required to load C++ extensions")
RuntimeError: Ninja is required to load C++ extensions