def train()

in train.py [0:0]

• 60 lines of code
• 20 McCabe index (conditional complexity)

def train(sess, model, hps, logdir, visualise):
    _print(hps)
    _print('Starting training. Logging to', logdir)
    _print('epoch n_processed n_images ips dtrain dtest dsample dtot train_results test_results msg')

    # Train
    sess.graph.finalize()
    n_processed = 0
    n_images = 0
    train_time = 0.0
    test_loss_best = 999999

    if hvd.rank() == 0:
        train_logger = ResultLogger(logdir + "train.txt", **hps.__dict__)
        test_logger = ResultLogger(logdir + "test.txt", **hps.__dict__)

    tcurr = time.time()
    for epoch in range(1, hps.epochs):

        t = time.time()

        train_results = []
        for it in range(hps.train_its):

            # Set learning rate, linearly annealed from 0 in the first hps.epochs_warmup epochs.
            lr = hps.lr * min(1., n_processed /
                              (hps.n_train * hps.epochs_warmup))

            # Run a training step synchronously.
            _t = time.time()
            train_results += [model.train(lr)]
            if hps.verbose and hvd.rank() == 0:
                _print(n_processed, time.time()-_t, train_results[-1])
                sys.stdout.flush()

            # Images seen wrt anchor resolution
            n_processed += hvd.size() * hps.n_batch_train
            # Actual images seen at current resolution
            n_images += hvd.size() * hps.local_batch_train

        train_results = np.mean(np.asarray(train_results), axis=0)

        dtrain = time.time() - t
        ips = (hps.train_its * hvd.size() * hps.local_batch_train) / dtrain
        train_time += dtrain

        if hvd.rank() == 0:
            train_logger.log(epoch=epoch, n_processed=n_processed, n_images=n_images, train_time=int(
                train_time), **process_results(train_results))

        if epoch < 10 or (epoch < 50 and epoch % 10 == 0) or epoch % hps.epochs_full_valid == 0:
            test_results = []
            msg = ''

            t = time.time()
            # model.polyak_swap()

            if epoch % hps.epochs_full_valid == 0:
                # Full validation run
                for it in range(hps.full_test_its):
                    test_results += [model.test()]
                test_results = np.mean(np.asarray(test_results), axis=0)

                if hvd.rank() == 0:
                    test_logger.log(epoch=epoch, n_processed=n_processed,
                                    n_images=n_images, **process_results(test_results))

                    # Save checkpoint
                    if test_results[0] < test_loss_best:
                        test_loss_best = test_results[0]
                        model.save(logdir+"model_best_loss.ckpt")
                        msg += ' *'

            dtest = time.time() - t

            # Sample
            t = time.time()
            if epoch == 1 or epoch == 10 or epoch % hps.epochs_full_sample == 0:
                visualise(epoch)
            dsample = time.time() - t

            if hvd.rank() == 0:
                dcurr = time.time() - tcurr
                tcurr = time.time()
                _print(epoch, n_processed, n_images, "{:.1f} {:.1f} {:.1f} {:.1f} {:.1f}".format(
                    ips, dtrain, dtest, dsample, dcurr), train_results, test_results, msg)

            # model.polyak_swap()

    if hvd.rank() == 0:
        _print("Finished!")