import yt
import numpy as np

npart = 1024
data = dict(particle_density = np.random.random(size=npart),
            particle_position_x = np.random.random(size=npart),
            particle_position_y = np.random.random(size=npart),
            particle_position_z = np.random.random(size=npart)
           )
ds = yt.load_particles(data, bbox = np.array([[0.0, 1.0], [0.0, 1.0], [0.0, 1.0]]))
level = ds.index.max_level
dims = ds.domain_dimensions * ds.refine_by**level
# This works
#cg = ds.covering_grid(level, left_edge=ds.domain_left_edge, dims = dims)
# This does not work
cg = ds.smoothed_covering_grid(level, left_edge=ds.domain_left_edge, dims = dims)

print cg['all_count'].shape