class_docstr: This class enables the extraction of image features (Harilick
  features) and basic statistics over a segmentation
class_docstr_tok: ["This","class","enables","the","extraction","of","image","features","(","Harilick","features",")","and","basic","statistics","over","a","segmentation"]
docstr: calculates the first quartile of the image over the binarised
  segmentation
  
  :return:
docstr_tok: ["calculates","the","first","quartile","of","the","image","over","the","binarised","segmentation",":","return",":"]
code: def quantile_25(self):
      """
      calculates the first quartile of the image over the binarised
      segmentation
  
      :return:
      """
      return mstats.mquantiles(
          self.masked_img, prob=0.25, axis=0
      ).flatten()
  
imports: from __future__ import absolute_import, print_function, division
  import numpy
  import numpy.ma
  import math
  import scipy.stats.mstats
  import scipy.ndimage
  from niftynet.utilities.util_common import MorphologyOps, CacheFunctionOutput
label_desc: Use image node_id 45 for calling the RegionProperties obj's underlying member method code with example usage: obj.quantile_25() and returns: mstats