code: def imbalance_check(P):
      """
      Check if the dataset is imbalanced.
  
      :param P: number of actual positives per class
      :type P: dict
      :return: is_imbalanced as bool
      """
      p_list = list(P.values())
      max_value = max(p_list)
      min_value = min(p_list)
      if min_value > 0:
          balance_ratio = max_value / min_value
      else:
          balance_ratio = max_value
      is_imbalanced = False
      if balance_ratio > BALANCE_RATIO_THRESHOLD:
          is_imbalanced = True
      return is_imbalanced
  
imports: from __future__ import division
  import sys
  import math
  import numpy
  import re
  from .pycm_param import *
  from .pycm_error import pycmMatrixError
  from warnings import warn
  from functools import wraps
label_desc: Use image node_id 18 for calling a global function with example usage: imbalance_check(P) and returns: is_imbalanced