class_docstr: This class represents a collection of atoms arranged in 3D space.
  
  An instance of this class may represent any collection of atoms: a molecule,
  a fragment of a molecule, multiple interacting molecules, a material, etc.
  For each atom it stores a position and a list of scalar properties.  Arbitrary
  properties are supported, but convenience methods are provided for accessing
  certain standard ones: atomic number, formal charge, and partial charge.
  
  Instances of this class are most often created by AtomicConformationFeaturizer.
  
  Attributes
  ----------
  positions: ndarray
      the positions of all atoms in Angstroms, stored in an array of shape (N, 3)
      where N is the number of atoms
  properties: ndarray
      the property values for all atoms, stored in an array of shape (N, M) where
      N is the number of atoms and M is the number of properties
  property_names: ndarray
      an array of length M with the names of the properties
docstr: Get the number of atoms in this object.
docstr_tok: ["Get","the","number","of","atoms","in","this","object","."]
code: def num_atoms(self) -> int:
      """Get the number of atoms in this object."""
      return self.positions.shape[0]
  
file_path: deepchem/deepchem/feat/atomic_conformation.py
imports: import numpy
  from deepchem.feat.base_classes import Featurizer
  from deepchem.utils import get_partial_charge
  from typing import Sequence
label_desc: Use image node_id 2 for calling the AtomicConformation obj's underlying member method code with example usage: obj.num_atoms() and returns: self