//  [python]
def train(self):
        """
        train model
        :return:
        """
        gpu_options = tf.GPUOptions(per_process_gpu_memory_fraction=0.5, allow_growth=True)
        sess_config = tf.ConfigProto(log_device_placement=False, allow_soft_placement=True, gpu_options=gpu_options)
        with tf.Session(config=sess_config) as sess:
            # init all variable in graph
            sess.run(tf.initialize_all_variables())
            current_step = 0

            for epoch in range(self.config["epochs"]):
                print("----- Epoch {}/{} -----".format(epoch + 1, self.config["epochs"]))
                for batch in self.train_data_obj.next_batch(self.train_tasks):
                    loss, predictions = self.model.train(sess, batch, self.config["keep_prob"])
                    label_list = list(set(batch["labels"]))
                    acc, recall, prec, f_beta = get_multi_metrics(pred_y=predictions, true_y=batch["labels"],
                                                                  labels=label_list)
                    print("train: step: {}, loss: {}, acc: {}, recall: {}, precision: {}, f_beta: {}".format(
                        current_step, loss, acc, recall, prec, f_beta))

                    current_step += 1
                    if current_step % self.config["checkpoint_every"] == 0:
                        eval_losses = []
                        eval_accs = []
                        eval_recalls = []
                        eval_precs = []
                        eval_f_betas = []
                        for eval_batch in self.train_data_obj.next_batch(self.eval_tasks):
                            eval_loss, eval_predictions = self.model.eval(sess, eval_batch)
                            eval_losses.append(eval_loss)
                            eval_label_list = list(set(eval_batch["labels"]))
                            acc, recall, prec, f_beta = get_multi_metrics(pred_y=eval_predictions,
                                                                          true_y=eval_batch["labels"],
                                                                          labels=eval_label_list)
                            eval_accs.append(acc)
                            eval_recalls.append(recall)
                            eval_precs.append(prec)
                            eval_f_betas.append(f_beta)
                        print("\n")
                        print("eval:  loss: {}, acc: {}, recall: {}, precision: {}, f_beta: {}".format(
                            mean(eval_losses), mean(eval_accs), mean(eval_recalls),
                            mean(eval_precs), mean(eval_f_betas)))
                        print("\n")

                        if self.config["ckpt_model_path"]:
                            save_path = os.path.join(os.path.abspath(os.getcwd()),
                                                     self.config["ckpt_model_path"])
                            if not os.path.exists(save_path):
                                os.makedirs(save_path)
                            model_save_path = os.path.join(save_path, self.config["model_name"])
                            self.model.saver.save(sess, model_save_path, global_step=current_step)