def summarize_dirs(self): """ Get the best and worst epochs of all given folders as a dict. Returns ------- minima : dict Keys : Name of folder. Values : [Epoch, metric] of where the metric is lowest. maxima : dict As above, but for where the metric is highest. """ minima, maxima = {}, {} for folder_no, folder in enumerate(self.folders): hist = HistoryHandler(folder) smry_met_name = self._full_metrics[folder_no] try: max_line = hist.get_best_epoch_info(metric=smry_met_name, mini=False) min_line = hist.get_best_epoch_info(metric=smry_met_name, mini=True) except OSError as e: warnings.warn(str(e)) continue minima[folder] = [min_line["Epoch"], min_line[smry_met_name]] maxima[folder] = [max_line["Epoch"], max_line[smry_met_name]] return minima, maxima
def __init__(self, output_folder, list_file=None, config_file=None, tf_log_level=None, discover_tomls=True): """ Set the attributes of the Configuration object. Instead of using a config_file, the attributes of orga.cfg can also be changed directly, e.g. by calling orga.cfg.batchsize. Parameters ---------- output_folder : str Name of the folder of this model in which everything will be saved, e.g., the summary.txt log file is located in here. Will be used to load saved files or to save new ones. list_file : str, optional Path to a toml list file with pathes to all the h5 files that should be used for training and validation. Will be used to extract samples and labels. Default: Look for a file called 'list.toml' in the given output_folder. config_file : str, optional Path to a toml config file with settings that are used instead of the default ones. Default: Look for a file called 'config.toml' in the given output_folder. tf_log_level : int/str Sets the TensorFlow CPP_MIN_LOG_LEVEL environment variable. 0 = all messages are logged (default behavior). 1 = INFO messages are not printed. 2 = INFO and WARNING messages are not printed. 3 = INFO, WARNING, and ERROR messages are not printed. discover_tomls : bool If False, do not try to look for toml files in the given output_folder if list_file or config_file is None [Default: True]. """ if tf_log_level is not None: os.environ['TF_CPP_MIN_LOG_LEVEL'] = str(tf_log_level) if discover_tomls and list_file is None: list_file = orcanet.misc.find_file(output_folder, "list.toml") if discover_tomls and config_file is None: config_file = orcanet.misc.find_file(output_folder, "config.toml") self.cfg = Configuration(output_folder, list_file, config_file) self.io = IOHandler(self.cfg) self.history = HistoryHandler(output_folder) self.xs_mean = None self._auto_label_modifier = None self._stored_model = None self._strategy = None
def _summarize_folder(self, folder_no): label = self.labels[folder_no] folder = self.folders[folder_no] hist = HistoryHandler(folder) val_data, min_stat, max_stat = None, None, None # read data from summary file try: smry_met_name = self._full_metrics[folder_no] max_line = hist.get_best_epoch_info(metric=smry_met_name, mini=False) min_line = hist.get_best_epoch_info(metric=smry_met_name, mini=True) min_stat = [min_line[smry_met_name], label, min_line["Epoch"]] max_stat = [max_line[smry_met_name], label, max_line["Epoch"]] summary_data = hist.get_summary_data() val_data = [ summary_data["Epoch"], summary_data[self._full_metrics[folder_no]] ] except OSError: if self.verbose: print(f"Warning: No summary file found for {folder}") except ValueError as e: if self.verbose: print(f"Error reading summary file {hist.summary_file} ({e})") # read data from training files full_train_data = hist.get_train_data() train_data = [ full_train_data["Batch_float"], full_train_data[self._metric_names[folder_no]] ] if not self.noplot: if len(self.labels) == 1: train_label, val_label = "training", "validation" elif val_data is None: train_label, val_label = label, None else: train_label, val_label = None, label self._tvp.plot_curves(train_data=train_data, val_data=val_data, train_label=train_label, val_label=val_label, smooth_sigma=self.smooth, tlw=0.5 * self.width, vlw=0.5 * self.width, vms=3 * self.width**0.5) return min_stat, max_stat
class TestHistoryHandler(TestCase): """ Test the in out Handler on 2 dummy summary files (summary.txt, summary_2.txt). """ def setUp(self): self.output_folder = os.path.join(os.path.dirname(__file__), "data", "dummy_model") self.history = HistoryHandler(self.output_folder) self.summary_filename_2 = "summary_2.txt" def test_get_metrics(self): metrics = self.history.get_metrics() target = ["loss", "acc"] np.testing.assert_array_equal(metrics, target) def test_get_summary_data(self): summary_data = self.history.get_summary_data() target = np.array( [(0.03488, 0.005, 0.07776, 0.05562, 0.971, 0.9808), (0.06971, 0.00465, 0.05034, np.nan, 0.9822, np.nan)], dtype=[('Epoch', '<f8'), ('LR', '<f8'), ('train_loss', '<f8'), ('val_loss', '<f8'), ('train_acc', '<f8'), ('val_acc', '<f8')]) assert_equal_struc_array(summary_data, target) def test_get_train_data(self): train_data = self.history.get_train_data() print(train_data) target = np.array([(250., 0.00018755, 0.487258, 0.756687), (500., 0.00056265, 0.291661, 0.874188), (250., 0.0350691, 0.0589843, 0.977938), (500., 0.0354442, 0.0554589, 0.980375)], dtype=[('Batch', '<f8'), ('Batch_float', '<f8'), ('loss', '<f8'), ('acc', '<f8')]) assert_equal_struc_array(train_data, target) def test_get_column_names(self): column_names = self.history.get_column_names() target = ('Epoch', 'LR', 'train_loss', 'val_loss', 'train_acc', 'val_acc') self.assertSequenceEqual(column_names, target) def test_get_state(self): self.history.summary_filename = self.summary_filename_2 state = self.history.get_state() print(state) target = [ { 'epoch': 0.1, 'is_trained': True, 'is_validated': True }, { 'epoch': 0.2, 'is_trained': False, 'is_validated': True }, { 'epoch': 0.3, 'is_trained': True, 'is_validated': False }, { 'epoch': 0.4, 'is_trained': False, 'is_validated': False }, ] self.assertSequenceEqual(state, target) def test_plot_metric_unknown_metric(self): with self.assertRaises(ValueError): self.history.plot_metric("test") """ @patch('orcanet.history.plot_history') def test_plot_metric_loss(self, mock_plot_history): def plot_history(train_data, val_data, **kwargs): return train_data, val_data, kwargs mock_plot_history.side_effect = plot_history value_train, value_val, value_kwargs = self.history.plot_metric("loss") target_train = [ np.array([0.000187551, 0.000562653, 0.0350691, 0.0354442]), np.array([0.487258, 0.291661, 0.0589843, 0.0554589]), ] target_val = [ np.array([0.03488, 0.06971]), np.array([0.05562, np.nan]), ] target_kwargs = {'y_label': 'loss'} np.testing.assert_array_almost_equal(target_train, value_train) np.testing.assert_array_almost_equal(target_val, value_val) self.assertDictEqual(target_kwargs, value_kwargs) @patch('orcanet.history.plot_history') def test_plot_metric_acc(self, mock_plot_history): def plot_history(train_data, val_data, **kwargs): return train_data, val_data, kwargs mock_plot_history.side_effect = plot_history value_train, value_val, value_kwargs = self.history.plot_metric("acc") target_train = [ np.array([0.000187551, 0.000562653, 0.0350691, 0.0354442]), np.array([0.756687, 0.874188, 0.977938, 0.980375]), ] target_val = [ np.array([0.03488, 0.06971]), np.array([0.9808, np.nan]), ] target_kwargs = {'y_label': 'acc'} np.testing.assert_array_almost_equal(target_train, value_train) np.testing.assert_array_almost_equal(target_val, value_val) self.assertDictEqual(target_kwargs, value_kwargs) @patch('orcanet.history.plot_history') def test_plot_lr(self, mock_plot_history): def plot_history(train_data, val_data, **kwargs): return train_data, val_data, kwargs mock_plot_history.side_effect = plot_history value_train, value_val, value_kwargs = self.history.plot_lr() target_train = None target_val = [ np.array([0.03488, 0.06971]), np.array([0.005, 0.00465]) ] target_kwargs = { 'y_label': 'Learning rate', 'legend': False } self.assertEqual(target_train, value_train) np.testing.assert_array_almost_equal(target_val, value_val) self.assertDictEqual(target_kwargs, value_kwargs) """ def test_get_best_epoch_info(self): self.history.summary_filename = self.summary_filename_2 value = self.history.get_best_epoch_info() target = np.array([(0.1, 0.11, 0.12, 0.13, 0.14, 0.15)], dtype=[('Epoch', '<f8'), ('LR', '<f8'), ('train_loss', '<f8'), ('val_loss', '<f8'), ('train_acc', '<f8'), ('val_acc', '<f8')]) np.testing.assert_array_equal(target, value) def test_get_best_epoch_fileno(self): self.history.summary_filename = self.summary_filename_2 value = self.history.get_best_epoch_fileno() target = (1, 1) self.assertEqual(target, value)
def setUp(self): self.output_folder = os.path.join(os.path.dirname(__file__), "data", "dummy_model") self.history = HistoryHandler(self.output_folder) self.summary_filename_2 = "summary_2.txt"
class Organizer: """ Core class for working with networks in OrcaNet. Attributes ---------- cfg : orcanet.core.Configuration Contains all configurable options. io : orcanet.in_out.IOHandler Utility functions for accessing the info in cfg. history : orcanet.in_out.HistoryHandler For reading and plotting data from the log files created during training. """ def __init__(self, output_folder, list_file=None, config_file=None, tf_log_level=None, discover_tomls=True): """ Set the attributes of the Configuration object. Instead of using a config_file, the attributes of orga.cfg can also be changed directly, e.g. by calling orga.cfg.batchsize. Parameters ---------- output_folder : str Name of the folder of this model in which everything will be saved, e.g., the summary.txt log file is located in here. Will be used to load saved files or to save new ones. list_file : str, optional Path to a toml list file with pathes to all the h5 files that should be used for training and validation. Will be used to extract samples and labels. Default: Look for a file called 'list.toml' in the given output_folder. config_file : str, optional Path to a toml config file with settings that are used instead of the default ones. Default: Look for a file called 'config.toml' in the given output_folder. tf_log_level : int/str Sets the TensorFlow CPP_MIN_LOG_LEVEL environment variable. 0 = all messages are logged (default behavior). 1 = INFO messages are not printed. 2 = INFO and WARNING messages are not printed. 3 = INFO, WARNING, and ERROR messages are not printed. discover_tomls : bool If False, do not try to look for toml files in the given output_folder if list_file or config_file is None [Default: True]. """ if tf_log_level is not None: os.environ['TF_CPP_MIN_LOG_LEVEL'] = str(tf_log_level) if discover_tomls and list_file is None: list_file = orcanet.misc.find_file(output_folder, "list.toml") if discover_tomls and config_file is None: config_file = orcanet.misc.find_file(output_folder, "config.toml") self.cfg = Configuration(output_folder, list_file, config_file) self.io = IOHandler(self.cfg) self.history = HistoryHandler(output_folder) self.xs_mean = None self._auto_label_modifier = None self._stored_model = None self._strategy = None def train_and_validate(self, model=None, epochs=None, to_epoch=None): """ Train a model and validate according to schedule. The various settings of this process can be controlled with the attributes of orca.cfg. The model will be trained on the given data, saved and validated. Logfiles of the training are saved in the output folder. Plots showing the training and validation history, as well as the weights and activations of the network are generated in the plots subfolder after every validation. The training can be resumed by executing this function again. Parameters ---------- model : ks.models.Model or str, optional Compiled keras model to use for training. Required for the first epoch (the start of training). Can also be the path to a saved keras model, which will be laoded. If model is None, the most recent saved model will be loaded automatically to continue the training. epochs : int, optional How many epochs should be trained by running this function. None for infinite. This includes the current epoch in case it is not finished yet, i.e. 1 means complete the epoch if there are files left, otherwise do the next epoch. to_epoch : int, optional Train up to and including this epoch. Can not be used together with epochs. Returns ------- model : ks.models.Model The trained keras model. """ latest_epoch = self.io.get_latest_epoch() model = self._get_model(model, logging=False) self._stored_model = model # check if the validation is missing for the latest fileno if latest_epoch is not None: state = self.history.get_state()[-1] if state["is_validated"] is False and self.val_is_due(latest_epoch): self.validate() next_epoch = self.io.get_next_epoch(latest_epoch) n_train_files = self.io.get_no_of_files("train") if to_epoch is None: epochs_left = epochs else: if epochs is not None: raise ValueError("Can not give both 'epochs' and 'to_epoch'") if latest_epoch is None: epochs_left = to_epoch else: epochs_left = max( 0, to_epoch - self.io.get_next_epoch(latest_epoch)[0] + 1) trained_epochs = 0 while epochs_left is None or trained_epochs < epochs_left: # Train on remaining files for file_no in range(next_epoch[1], n_train_files + 1): curr_epoch = (next_epoch[0], file_no) self.train(model) if self.val_is_due(curr_epoch): self.validate() next_epoch = (next_epoch[0] + 1, 1) trained_epochs += 1 self._stored_model = None return model def train(self, model=None): """ Trains a model on the next file. The progress of the training is also logged and plotted. Parameters ---------- model : ks.models.Model or str, optional Compiled keras model to use for training. Required for the first epoch (the start of training). Can also be the path to a saved keras model, which will be laoded. If model is None, the most recent saved model will be loaded automatically to continue the training. Returns ------- history : dict The history of the training on this file. A record of training loss values and metrics values. """ # Create folder structure self.io.get_subfolder(create=True) latest_epoch = self.io.get_latest_epoch() model = self._get_model(model, logging=True) self._set_up(model, logging=True) # epoch about to be trained next_epoch = self.io.get_next_epoch(latest_epoch) next_epoch_float = self.io.get_epoch_float(*next_epoch) if latest_epoch is None: self.io.check_connections(model) logging.log_start_training(self) model_path = self.io.get_model_path(*next_epoch) model_path_local = self.io.get_model_path(*next_epoch, local=True) if os.path.isfile(model_path): raise FileExistsError( "Can not train model in epoch {} file {}, this model has " "already been saved!".format(*next_epoch)) smry_logger = logging.SummaryLogger(self, model) if self.cfg.learning_rate is not None: tf.keras.backend.set_value( model.optimizer.lr, self.io.get_learning_rate(next_epoch) ) files_dict = self.io.get_file("train", next_epoch[1]) line = "Training in epoch {} on file {}/{}".format( next_epoch[0], next_epoch[1], self.io.get_no_of_files("train")) self.io.print_log(line) self.io.print_log("-" * len(line)) self.io.print_log("Learning rate is at {}".format( tf.keras.backend.get_value(model.optimizer.lr))) self.io.print_log('Inputs and files:') for input_name, input_file in files_dict.items(): self.io.print_log(" {}: \t{}".format(input_name, os.path.basename( input_file))) start_time = time.time() history = backend.train_model(self, model, next_epoch, batch_logger=True) elapsed_s = int(time.time() - start_time) model.save(model_path) smry_logger.write_line( next_epoch_float, tf.keras.backend.get_value(model.optimizer.lr), history_train=history, ) self.io.print_log('Training results:') for metric_name, loss in history.items(): self.io.print_log(f" {metric_name}: \t{loss}") self.io.print_log(f"Elapsed time: {timedelta(seconds=elapsed_s)}") self.io.print_log(f"Saved model to: {model_path_local}\n") update_summary_plot(self) if self.cfg.cleanup_models: self.cleanup_models() return history def validate(self): """ Validate the most recent saved model on all validation files. Will also log the progress, as well as update the summary plot and plot weights and activations of the model. Returns ------- history : dict The history of the validation on all files. A record of validation loss values and metrics values. """ latest_epoch = self.io.get_latest_epoch() if latest_epoch is None: raise ValueError("Can not validate: No saved model found") if self.history.get_state()[-1]["is_validated"] is True: raise ValueError("Can not validate in epoch {} file {}: " "Has already been validated".format(*latest_epoch)) if self._stored_model is None: model = self.load_saved_model(*latest_epoch) else: model = self._stored_model self._set_up(model, logging=True) epoch_float = self.io.get_epoch_float(*latest_epoch) smry_logger = logging.SummaryLogger(self, model) logging.log_start_validation(self) start_time = time.time() history = backend.validate_model(self, model) elapsed_s = int(time.time() - start_time) self.io.print_log('Validation results:') for metric_name, loss in history.items(): self.io.print_log(f" {metric_name}: \t{loss}") self.io.print_log(f"Elapsed time: {timedelta(seconds=elapsed_s)}\n") smry_logger.write_line(epoch_float, "n/a", history_val=history) update_summary_plot(self) if self.cfg.cleanup_models: self.cleanup_models() return history def predict(self, epoch=None, fileno=None, samples=None): """ Make a prediction if it does not exist yet, and return its filepath. Load the model with the lowest validation loss, let it predict on all samples of the validation set in the toml list, and save this prediction together with all the y_values as h5 file(s) in the predictions subfolder. Parameters ---------- epoch : int, optional Epoch of a model to load. Default: lowest val loss. fileno : int, optional File number of a model to load. Default: lowest val loss. samples : int, optional Don't use the full validation files, but just the given number of samples. Returns ------- pred_filename : List List to the paths of all the prediction files. """ if fileno is None and epoch is None: epoch, fileno = self.history.get_best_epoch_fileno() print(f"Automatically set epoch to epoch {epoch} file {fileno}.") elif fileno is None or epoch is None: raise ValueError( "Either both or none of epoch and fileno must be None") if self._check_if_pred_already_done(epoch, fileno): print("Prediction has already been done.") pred_filepaths = self.io.get_pred_files_list(epoch, fileno) else: if self._stored_model is None: model = self.load_saved_model(epoch, fileno, logging=False) else: model = self._stored_model self._set_up(model) start_time = time.time() backend.make_model_prediction( self, model, epoch, fileno, samples=samples) elapsed_s = int(time.time() - start_time) print('Finished predicting on all validation files.') print("Elapsed time: {}\n".format(timedelta(seconds=elapsed_s))) pred_filepaths = self.io.get_pred_files_list(epoch, fileno) return pred_filepaths def inference(self, epoch=None, fileno=None, as_generator=False): """ Make an inference and return the filepaths. Load the model with the lowest validation loss, let it predict on all samples of all inference files in the toml list, and save these predictions as h5 files in the predictions subfolder. y values will only be added if they are in the input file, so this can be used on un-labeled data as well. Parameters ---------- epoch : int, optional Epoch of a model to load [default: lowest val loss]. fileno : int, optional File number of a model to load [default: lowest val loss]. as_generator : bool If true, return a generator, which yields the output filename after the inference of each file. If false (default), do all files back to back. Returns ------- filenames : list List to the paths of all created output files. """ if fileno is None and epoch is None: epoch, fileno = self.history.get_best_epoch_fileno() print("Automatically set epoch to epoch {} file {}.".format(epoch, fileno)) elif fileno is None or epoch is None: raise ValueError( "Either both or none of epoch and fileno must be None") if self._stored_model is None: model = self.load_saved_model(epoch, fileno, logging=False) else: model = self._stored_model self._set_up(model) filenames = [] for files_dict in self.io.yield_files("inference"): # output filename is based on name of file in first input first_filename = os.path.basename(list(files_dict.values())[0]) output_filename = "model_epoch_{}_file_{}_on_{}".format( epoch, fileno, first_filename) output_path = os.path.join(self.io.get_subfolder("inference"), output_filename) filenames.append(output_path) if os.path.exists(output_path): warnings.warn("Warning: {} exists already, skipping " "file".format(output_filename)) continue print(f'Working on file {first_filename}') start_time = time.time() backend.h5_inference( self, model, files_dict, output_path, use_def_label=False) elapsed_s = int(time.time() - start_time) print(f'Finished on file {first_filename} in {elapsed_s/60} min') if as_generator: yield output_path return filenames def cleanup_models(self): """ Delete all models except for the the most recent one (to continue training), and the ones with the highest and lowest loss/metrics. """ all_epochs = self.io.get_all_epochs() epochs_to_keep = {self.io.get_latest_epoch(), } try: for metric in self.history.get_metrics(): epochs_to_keep.add( self.history.get_best_epoch_fileno( metric=f"val_{metric}", mini=True)) epochs_to_keep.add( self.history.get_best_epoch_fileno( metric=f"val_{metric}", mini=False)) except ValueError: # no best epoch exists pass for epoch in epochs_to_keep: if epoch not in all_epochs: warnings.warn( f"ERROR: keeping_epoch {epoch} not in available epochs {all_epochs}, " f"skipping clean-up of models!") return print("\nClean-up saved models:") for epoch in all_epochs: model_path = self.io.get_model_path(epoch[0], epoch[1]) model_name = os.path.basename(model_path) if epoch in epochs_to_keep: print("Keeping model {}".format(model_name)) else: print("Deleting model {}".format(model_name)) os.remove(model_path) def _check_if_pred_already_done(self, epoch, fileno): """ Checks if the prediction has already been done before. (-> predicted on all validation files) Returns ------- pred_done : bool Boolean flag to specify if the prediction has already been fully done or not. """ latest_pred_file_no = self.io.get_latest_prediction_file_no(epoch, fileno) total_no_of_val_files = self.io.get_no_of_files('val') if latest_pred_file_no is None: pred_done = False elif latest_pred_file_no == total_no_of_val_files: return True else: pred_done = False return pred_done def get_xs_mean(self, logging=False): """ Set and return the zero center image for each list input. Requires the cfg.zero_center_folder to be set. If no existing image for the given input files is found in the folder, it will be calculated and saved by averaging over all samples in the train dataset. Parameters ---------- logging : bool If true, the execution of this function will be logged into the full summary in the output folder if called for the first time. Returns ------- dict Dict of numpy arrays that contains the mean_image of the x dataset (1 array per list input). Example format: { "input_A" : ndarray, "input_B" : ndarray } """ if self.xs_mean is None: if self.cfg.zero_center_folder is None: raise ValueError("Can not calculate zero center: " "No zero center folder given") self.xs_mean = load_zero_center_data(self, logging=logging) return self.xs_mean def load_saved_model(self, epoch, fileno, logging=False): """ Load a saved model. Parameters ---------- epoch : int Epoch of the saved model. If both this and fileno are -1, load the most recent model. fileno : int Fileno of the saved model. logging : bool If True, will log this function call into the log.txt file. Returns ------- model : keras model """ path_of_model = self.io.get_model_path(epoch, fileno) path_loc = self.io.get_model_path(epoch, fileno, local=True) self.io.print_log("Loading saved model: " + path_loc, logging=logging) return self._load_model(path_of_model) def _get_model(self, model, logging=False): """ Load most recent saved model or use user model. """ latest_epoch = self.io.get_latest_epoch() if latest_epoch is None: # new training, log info about model if model is None: raise ValueError("You need to provide a compiled keras model " "for the start of the training! (You gave None)") elif isinstance(model, str): # path to a saved model self.io.print_log("Loading model from " + model, logging=logging) model = self._load_model(model) if logging: self._save_as_json(model) model.summary(print_fn=self.io.print_log) try: plots_folder = self.io.get_subfolder("plots", create=True) tf.keras.utils.plot_model( model, plots_folder + "/model_plot.png", show_shapes=True) except (ImportError, AttributeError) as e: # TODO remove AttributeError once https://github.com/tensorflow/tensorflow/issues/38988 is fixed warnings.warn("Can not plot model: " + str(e)) else: # resuming training, load model if it is not given if model is None: model = self.load_saved_model(*latest_epoch, logging=logging) elif isinstance(model, str): # path to a saved model self.io.print_log("Loading model from " + model, logging=logging) model = self._load_model(model) return model def _load_model(self, filepath): """ Load from path, with custom objects and parallized. """ with self.get_strategy().scope(): model = tf.keras.models.load_model( filepath, custom_objects=self.cfg.get_custom_objects()) return model def _save_as_json(self, model): """ Save the architecture of a model as json to fixed path. """ json_filename = "model_arch.json" json_string = model.to_json(indent=1) model_folder = self.io.get_subfolder("saved_models", create=True) with open(os.path.join(model_folder, json_filename), "w") as f: f.write(json_string) def _set_up(self, model, logging=False): """ Necessary setup for training, validating and predicting. """ if self.cfg.get_list_file() is None: raise ValueError("No files specified. Need to load a toml " "list file with pathes to h5 files first.") if self.cfg.label_modifier is None: self._auto_label_modifier = lib.label_modifiers.ColumnLabels(model) if self.cfg.zero_center_folder is not None: self.get_xs_mean(logging) def val_is_due(self, epoch=None): """ True if validation is due on given epoch according to schedule. Does not check if it has been done already. """ if epoch is None: epoch = self.io.get_latest_epoch() n_train_files = self.io.get_no_of_files("train") val_sched = (epoch[1] == n_train_files) or \ (self.cfg.validate_interval is not None and epoch[1] % self.cfg.validate_interval == 0) return val_sched def get_strategy(self): """ Get the strategy for distributed training. """ if self._strategy is None: if self.cfg.multi_gpu and len( tf.config.list_physical_devices('GPU')) > 1: self._strategy = tf.distribute.MirroredStrategy() print(f'Number of GPUs: {self._strategy.num_replicas_in_sync}') else: self._strategy = tf.distribute.get_strategy() return self._strategy