class_docstr: Abstract class for confusion matrix
  
  You shouldn't instantiate this class.
  You might instantiate ConfusionMatrix or BinaryConfusionMatrix classes
class_docstr_tok: ["Abstract","class","for","confusion","matrix","You","should","n't","instantiate","this","class",".","You","might","instantiate","ConfusionMatrix","or","BinaryConfusionMatrix","classes"]
docstr: Returns len of a confusion matrix.
  For example: 3 means that this is a 3x3 (3 rows, 3 columns) matrix
docstr_tok: ["Returns","len","of","a","confusion","matrix",".","For","example",":","3","means","that","this","is","a","3x3","(","3","rows",",","3","columns",")","matrix"]
code: def len(self):
      """
      Returns len of a confusion matrix.
      For example: 3 means that this is a 3x3 (3 rows, 3 columns) matrix
      """
      return self._len
  
imports: import numpy
  import pandas
  import collections
  import pandas_ml
  from pandas_ml.confusion_matrix.stats import binom_interval, class_agreement, prop_test
label_desc: Use image node_id 12 for calling the ConfusionMatrixAbstract obj's underlying member method code with example usage: obj.len() and returns: self