code: def pixel_accuracy(self):
      if np.sum(self.confusion_matrix) == 0:
          print("Attention: pixel_total is zero!!!")
          PA = 0
      else:
          PA = (
              np.diag(self.confusion_matrix).sum()
              / self.confusion_matrix.sum()
          )
  
      return PA
  
imports: import os
  import time
  import tqdm
  import numpy
  from PIL import Image
  import paddle
  import paddle.nn.functional
  from paddleseg.utils import metrics, TimeAverager, calculate_eta, logger, progbar
  import datasets
  from utils import save_imgs
label_desc: Use image node_id 2 for calling the Eval obj's underlying member method code with example usage: obj.pixel_accuracy() and returns: PA