code: def extract_data(self):
          
          self.time_axis = []
          self.cpu_axis = []
          self.mem_axis = []
          self.timestamp_list = []
          plot_data = self.data.get("plot_data", [])
          # 按照时间分割线，划分成几段数据，取其中的最值
          for i in plot_data:
              timestamp = i["timestamp"]
              self.timestamp_list.append(timestamp)
              timestamp = round(timestamp, 1)
              cpu_percent = i["cpu_percent"]
              mem_gb_num = i["mem_gb_num"]
              date = datetime.fromtimestamp(timestamp)
              # 添加坐标轴
              self.time_axis.append(date)
              self.cpu_axis.append(cpu_percent)
              self.mem_axis.append(mem_gb_num)
  
          # 获取各种方法执行过程中的cpu和内存极值:
          self.get_each_method_maximun_cpu_mem()
docs: 从数据中获取到绘图相关的有用信息.