code: def _rank(p):
      return p["basis_vectors"].shape[1]
  
imports: import numpy
  import pytest
  from nibabel.affines import from_matvec
  from numpy.testing import assert_almost_equal, assert_array_equal
  from ....core.api import AffineTransform, Image
  from ....core.api import CoordinateSystem
  from ....core.image.image import rollimg
  from ....core.reference.coordinate_map import AxisError, drop_io_dim
  from ....core.reference.coordinate_map import product
  from ....io.api import load_image
  from ....testing import funcfile
  from ..pca import pca
  from ..pca import pca_image
  from .test_pca import res2pos1
label_desc: Use image node_id 2 for calling a global function with example usage: _rank(p) and returns: p