[template] OVITO python modifier

# Import OVITO modules.

from ovito.io import *
from ovito.modifiers import *
from ovito.data import *

# Import system and NumPy libraries
import sys
import numpy

# Define your own modifier
def modify(frame, input, output):

print("The input contains %i particles." % input.number_of_particles)

# Loop over particles and print their number of bonds.
for particle_index in range(output.number_of_particles):
    # Print particle index (1-based).
    sys.stdout.write("%i " % (particle_index+1))
    
    value1 = <your calculations>
    
    output.particle_proporties.['<key>'].marray[particle_index] = value1
    output.particle_proporties.['<key>'].changed()
    
    # End of particle line

        sys.stdout.write("\n")