docstr: Extract feature descriptors in image for given keypoints.
  
  Parameters
  ----------
  image : 2D array
      Input image.
  keypoints : (N, 2) array
      Keypoint locations as ``(row, col)``.
docstr_tok: ["Extract","feature","descriptors","in","image","for","given","keypoints",".","Parameters","--","--","--","--","--","image",":","2D","array","Input","image",".","keypoints",":","(","N",",","2",")","array","Keypoint","locations","as","``","(","row",",","col",")","``","."]
code: def extract(self, image, keypoints):
      """Extract feature descriptors in image for given keypoints.
  
      Parameters
      ----------
      image : 2D array
          Input image.
      keypoints : (N, 2) array
          Keypoint locations as ``(row, col)``.
  
      """
      raise NotImplementedError()
  
file_path: scikit-image/skimage/feature/util.py
imports: import numpy
  from ..util import img_as_float
  from .._shared.utils import _supported_float_type, check_nD
label_desc: Use image node_id 2 for calling the DescriptorExtractor obj's underlying member method code with example usage: obj.extract(image, keypoints) without return types