diff --git a/src/single-core-regen/regen.py b/src/single-core-regen/regen.py
new file mode 100644
index 0000000..c334e51
--- /dev/null
+++ b/src/single-core-regen/regen.py
@@ -0,0 +1,287 @@
+from dataclasses import dataclass
+from datetime import datetime
+import time
+import matplotlib.pyplot as plt
+
+import numpy as np
+import optuna
+import warnings
+
+import torch
+import torch.nn as nn
+import torch.functional as F
+import torch.optim as optim
+import torch.utils.data
+
+import multiprocessing
+
+from util.datasets import FiberRegenerationDataset
+import util
+
+
+# global settings
+@dataclass
+class GlobalSettings:
+    seed: int = 42
+
+
+# data settings
+@dataclass
+class DataSettings:
+    config_path: str = "data/*-128-16384-10000-0-0-17-0-PAM4-0.ini"
+    symbols_range: tuple = (1, 100)
+    data_size_range: tuple = (1, 20)
+    target_delay: float = 0
+    xy_delay_range: tuple = (0, 1)
+    drop_first: int = 1000
+    train_split: float = 0.8
+
+
+# pytorch settings
+@dataclass
+class PytorchSettings:
+    device: str = "cuda"
+    batchsize: int = 128
+    epochs: int = 100
+
+
+# model settings
+@dataclass
+class ModelSettings:
+    output_size: int = 2
+    n_layer_range: tuple = (1, 3)
+    n_units_range: tuple = (4, 128)
+    activation_func_range: tuple = ("ReLU",)
+
+
+@dataclass
+class OptimizerSettings:
+    optimizer_range: tuple = ("Adam", "RMSprop", "SGD")
+    lr_range: tuple = (1e-5, 1e-1)
+
+
+# optuna settings
+@dataclass
+class OptunaSettings:
+    n_trials: int = 128
+    n_threads: int = 16
+    timeout: int = 600
+    directions: tuple = ("maximize",)
+
+    limit_examples: bool = True
+    n_train_examples: int = PytorchSettings.batchsize * 30
+    n_valid_examples: int = PytorchSettings.batchsize * 10
+    storage: str = "sqlite:///optuna_single_core_regen.db"
+    study_name: str = (
+        f"single_core_regen_{datetime.now().strftime('%Y-%m-%d %H:%M:%S')}"
+    )
+    metrics_names: tuple = ("accuracy",)
+
+class HyperTraining:
+    def __init__(self):
+        self.global_settings = GlobalSettings()
+        self.data_settings = DataSettings()
+        self.pytorch_settings = PytorchSettings()
+        self.model_settings = ModelSettings()
+        self.optimizer_settings = OptimizerSettings()
+        self.optuna_settings = OptunaSettings()
+
+        # set some extra settings to make the code more readable
+        self._extra_optuna_settings()
+    
+    def setup_study(self):
+        self.study = optuna.create_study(
+            study_name=self.optuna_settings.study_name,
+            storage=self.optuna_settings.storage,
+            load_if_exists=True,
+            direction=self.optuna_settings.direction,
+            directions=self.optuna_settings.directions,
+        )
+
+        with warnings.catch_warnings(action="ignore"):
+            self.study.set_metric_names(self.optuna_settings.metrics_names)
+        
+        self.n_threads = min(self.optuna_settings.n_trials, self.optuna_settings.n_threads)
+        self.processes = []
+        for _ in range(self.n_threads):
+            p = multiprocessing.Process(target=self._run_optimize)
+            self.processes.append(p)
+    
+    def run_study(self):
+        for p in self.processes:
+            p.start()
+        
+        for p in self.processes:
+            p.join()
+        
+        remaining_trials = self.optuna_settings.n_trials - self.optuna_settings.n_trials % self.optuna_settings.n_threads
+        if remaining_trials:
+            self._run_optimize(remaining_trials)
+    
+    def _run_optimize(self, n_trials):
+        self.study.optimize(self.objective, n_trials=n_trials, timeout=self.optuna_settings.timeout)
+
+    def eye(self, show=True):
+        util.plot.eye(self.data_settings.config_path, show=show)
+
+    def _extra_optuna_settings(self):
+        self.optuna_settings.multi_objective = len(self.optuna_settings.directions) > 1
+        if self.optuna_settings.multi_objective:
+            self.optuna_settings.direction = None
+        else:
+            self.optuna_settings.direction = self.optuna_settings.directions[0]
+            self.optuna_settings.directions = None
+
+        self.optuna_settings.n_train_examples = (
+            self.optuna_settings.n_train_examples
+            if self.optuna_settings.limit_examples
+            else float("inf")
+        )
+        self.optuna_settings.n_valid_examples = (
+            self.optuna_settings.n_valid_examples
+            if self.optuna_settings.limit_examples
+            else float("inf")
+        )
+
+    def define_model(self, trial: optuna.Trial):
+        n_layers = trial.suggest_int(
+            "model_n_layers", *self.model_settings.n_layer_range
+        )
+        layers = []
+
+        # REVIEW does that work?
+        in_features = trial.params["dataset_data_size"] * 2
+        for i in range(n_layers):
+            out_features = trial.suggest_int(
+                f"model_n_units_l{i}", *self.model_settings.n_units_range
+            )
+            activation_func = trial.suggest_categorical(
+                f"model_activation_func_l{i}", self.model_settings.activation_func_range
+            )
+
+            layers.append(nn.Linear(in_features, out_features))
+            layers.append(getattr(nn, activation_func))
+            in_features = out_features
+
+        layers.append(nn.Linear(in_features, self.model_settings.output_size))
+
+        return nn.Sequential(*layers)
+
+    def get_sliced_data(self, trial: optuna.Trial):
+        assert ModelSettings.input_size % 2 == 0, "input_dim must be even"
+        symbols = trial.suggest_float(
+            "dataset_symbols", *self.data_settings.symbols_range, log=True
+        )
+        xy_delay = trial.suggest_float(
+            "dataset_xy_delay", *self.data_settings.xy_delay_range
+        )
+        data_size = trial.suggest_int(
+            "dataset_data_size", *self.data_settings.data_size_range
+        )
+        # get dataset
+        dataset = FiberRegenerationDataset(
+            file_path=self.data_settings.config_path,
+            symbols=symbols,
+            data_size=data_size,  # two channels (x,y)
+            target_delay=self.data_settings.target_delay,
+            xy_delay=xy_delay,
+            drop_first=self.data_settings.drop_first,
+        )
+
+        dataset_size = len(dataset)
+        indices = list(range(dataset_size))
+        split = int(np.floor(self.data_settings.train_split * dataset_size))
+        np.random.seed(self.global_settings.seed)
+        np.random.shuffle(indices)
+        train_indices, valid_indices = indices[:split], indices[split:]
+
+        train_sampler = torch.utils.data.SubsetRandomSampler(train_indices)
+        valid_sampler = torch.utils.data.SubsetRandomSampler(valid_indices)
+
+        train_loader = torch.utils.data.DataLoader(
+            dataset, batch_size=self.pytorch_settings.batchsize, sampler=train_sampler
+        )
+        valid_loader = torch.utils.data.DataLoader(
+            dataset, batch_size=self.pytorch_settings.batchsize, sampler=valid_sampler
+        )
+
+        return train_loader, valid_loader
+
+
+    def train_model(self, model, optimizer, train_loader):
+        model.train()
+        for batch_idx, (data, target) in enumerate(train_loader):
+            if (batch_idx * train_loader.batchsize
+                >= self.optuna_settings.n_train_examples):
+                break
+            optimizer.zero_grad()
+            data, target = (
+                data.to(self.pytorch_settings.device),
+                target.to(self.pytorch_settings.device),
+            )
+            target_pred = model(data)
+            loss = F.mean_squared_error(target_pred, target)
+            loss.backward()
+            optimizer.step()
+
+
+    def eval_model(self, model, valid_loader):
+        model.eval()
+        correct = 0
+        with torch.no_grad():
+            for batch_idx, (data, target) in enumerate(valid_loader):
+                if (
+                    batch_idx * valid_loader.batchsize
+                    >= self.optuna_settings.n_valid_examples
+                ):
+                    break
+                data, target = (
+                    data.to(self.pytorch_settings.device),
+                    target.to(self.pytorch_settings.device),
+                )
+                target_pred = model(data)
+                pred = target_pred.argmax(dim=1, keepdim=True)
+                correct += pred.eq(target.view_as(pred)).sum().item()
+
+        accuracy = correct / len(valid_loader.dataset)
+        # num_params = sum(p.numel() for p in model.parameters())
+        return accuracy
+
+    def objective(self, trial: optuna.Trial):
+        model = self.define_model(trial).to(self.pytorch_settings.device)
+
+        optimizer_name = trial.suggest_categorical(
+            "optimizer", self.optimizer_settings.optimizer_range
+        )
+        lr = trial.suggest_float("lr", *self.optimizer_settings.lr_range, log=True)
+        optimizer = getattr(optim, optimizer_name)(model.parameters(), lr=lr)
+
+        train_loader, valid_loader = self.get_sliced_data(trial)
+
+        for epoch in range(self.pytorch_settings.epochs):
+            self.train_model(model, optimizer, train_loader)
+            accuracy = self.eval_model(model, valid_loader)
+
+            if len(self.optuna_settings.directions) == 1:
+                trial.report(accuracy, epoch)
+                if trial.should_prune():
+                    raise optuna.exceptions.TrialPruned()
+
+        return accuracy
+
+
+if __name__ == "__main__":
+    # plt.ion()
+    hyper_training = HyperTraining()
+    hyper_training.eye()
+
+    # hyper_training.setup_study()
+    # hyper_training.run_study()
+    for i in range(10):
+        #simulate some work
+        print(i)
+        time.sleep(0.2)
+
+    plt.show()
+    ...
+
diff --git a/src/single-core-regen/testing/learn_optuna.py b/src/single-core-regen/testing/learn_optuna.py
new file mode 100644
index 0000000..b700cc0
--- /dev/null
+++ b/src/single-core-regen/testing/learn_optuna.py
@@ -0,0 +1,194 @@
+from datetime import datetime
+from pathlib import Path
+
+import optuna
+import warnings
+from util.optuna_vis import show_figures
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import torch.optim as optim
+import torch.utils.data
+
+from torchvision import datasets
+from torchvision import transforms
+import multiprocessing
+
+# from util.dataset import SlicedDataset
+
+DEVICE = torch.device("cuda")
+BATCHSIZE = 128
+CLASSES = 10
+DIR = Path(__file__).parent
+EPOCHS = 100
+N_TRAIN_EXAMPLES = BATCHSIZE * 30
+N_VALID_EXAMPLES = BATCHSIZE * 10
+
+n_trials = 128
+n_threads = 16
+
+
+def define_model(trial):
+    n_layers = trial.suggest_int("n_layers", 1, 3)
+    layers = []
+
+    in_features = 28 * 28
+    for i in range(n_layers):
+        out_features = trial.suggest_int(f"n_units_l{i}", 4, 128)
+        layers.append(nn.Linear(in_features, out_features))
+        layers.append(nn.ReLU())
+        p = trial.suggest_float(f"dropout_l{i}", 0.2, 0.5)
+        layers.append(nn.Dropout(p))
+
+        in_features = out_features
+
+    layers.append(nn.Linear(in_features, CLASSES))
+    layers.append(nn.LogSoftmax(dim=1))
+
+    return nn.Sequential(*layers)
+
+
+def get_mnist():
+    # Load FashionMNIST dataset.
+    train_loader = torch.utils.data.DataLoader(
+        datasets.FashionMNIST(
+            DIR / ".data", train=True, download=True, transform=transforms.ToTensor()
+        ),
+        batch_size=BATCHSIZE,
+        shuffle=True,
+    )
+    valid_loader = torch.utils.data.DataLoader(
+        datasets.FashionMNIST(
+            DIR / ".data", train=False, transform=transforms.ToTensor()
+        ),
+        batch_size=BATCHSIZE,
+        shuffle=True,
+    )
+
+    return train_loader, valid_loader
+
+
+def objective(trial):
+    model = define_model(trial).to(DEVICE)
+
+    optimizer_name = trial.suggest_categorical("optimizer", ["Adam", "RMSprop", "SGD"])
+    lr = trial.suggest_float("lr", 1e-5, 1e-1, log=True)
+    optimizer = getattr(optim, optimizer_name)(model.parameters(), lr=lr)
+
+    train_loader, valid_loader = get_mnist()
+
+    for epoch in range(EPOCHS):
+        train_model(model, optimizer, train_loader)
+        accuracy, num_params = eval_model(model, valid_loader)
+
+    return accuracy, num_params
+
+
+def eval_model(model, valid_loader):
+    model.eval()
+    correct = 0
+    with torch.no_grad():
+        for batch_idx, (data, target) in enumerate(valid_loader):
+            if batch_idx * BATCHSIZE >= N_VALID_EXAMPLES:
+                break
+
+            data, target = data.view(data.size(0), -1).to(DEVICE), target.to(DEVICE)
+            output = model(data)
+
+            pred = output.argmax(dim=1, keepdim=True)
+            correct += pred.eq(target.view_as(pred)).sum().item()
+
+    accuracy = correct / min(len(valid_loader.dataset), N_VALID_EXAMPLES)
+    num_params = sum(p.numel() for p in model.parameters())
+    return accuracy, num_params
+
+
+def train_model(model, optimizer, train_loader):
+    model.train()
+    for batch_idx, (data, target) in enumerate(train_loader):
+        if batch_idx * BATCHSIZE >= N_TRAIN_EXAMPLES:
+            break
+
+        data, target = data.view(data.size(0), -1).to(DEVICE), target.to(DEVICE)
+
+        optimizer.zero_grad()
+        output = model(data)
+        loss = F.nll_loss(output, target)
+        loss.backward()
+        optimizer.step()
+
+
+def run_optimize(n_trials, study):
+    study.optimize(objective, n_trials=n_trials, timeout=600)
+
+
+if __name__ == "__main__":
+    study_name = f"{datetime.now().strftime('%Y-%m-%d %H:%M:%S')} mnist example"
+    storage = "sqlite:///db.sqlite3"
+    directions = ["maximize", "minimize"]
+
+    study = optuna.create_study(
+        directions=directions,
+        storage=storage,
+        study_name=study_name,
+    )
+    
+    with warnings.catch_warnings(action="ignore"):
+        study.set_metric_names(["accuracy", "num params"])
+
+    n_threads = min(n_trials, n_threads)
+
+    processes = []
+    for _ in range(n_threads):
+        p = multiprocessing.Process(
+            target=run_optimize, args=(n_trials // n_threads, study)
+        )
+        p.start()
+        processes.append(p)
+
+    for p in processes:
+        p.join()
+
+    remaining_trials = n_trials - ((n_trials // n_threads) * n_threads)
+    if remaining_trials:
+        print(
+            f"\nRunning last {remaining_trials} trial{'s' if remaining_trials > 1 else ''}:"
+        )
+        run_optimize(directions, remaining_trials, study_name, storage)
+
+    print(f"Number of trials on the Pareto front: {len(study.best_trials)}")
+
+    trial_with_highest_accuracy = max(study.best_trials, key=lambda t: t.values[1])
+    print("Trial with highest accuracy: ")
+    print(f"\tnumber: {trial_with_highest_accuracy.number}")
+    print(f"\tparams: {trial_with_highest_accuracy.params}")
+    print(f"\tvalues: {trial_with_highest_accuracy.values}")
+
+    # for trial in trials:
+    #     print(f"Trial {trial.number}")
+    #     print(f"  Accuracy: {trial.values[0]}")
+    #     print(f"  n_params: {int(trial.values[1])}")
+    #     print( "  Params: ")
+    #     for key, value in trial.params.items():
+    #         print("    {}: {}".format(key, value))
+    #     print()
+
+    # print("  Value: ", trial.value)
+
+    # print("  Params: ")
+    # for key, value in trial.params.items():
+    #     print("    {}: {}".format(key, value))
+
+    figures = []
+    figures.append(
+        optuna.visualization.plot_pareto_front(
+            study, target_names=["accuracy", "num_params"]
+        )
+    )
+    figures.append(optuna.visualization.plot_timeline(study))
+
+    plt = show_figures(*figures)
+
+    print()
+    # plt.show()
diff --git a/src/single-core-regen/util/__init__.py b/src/single-core-regen/util/__init__.py
new file mode 100644
index 0000000..9651fca
--- /dev/null
+++ b/src/single-core-regen/util/__init__.py
@@ -0,0 +1,3 @@
+from .datasets import FiberRegenerationDataset  # noqa: F401
+from .optuna_vis import show_figures # noqa: F401
+from .plot import eye # noqa: F401
\ No newline at end of file
diff --git a/src/single-core-regen/util/dataset.py b/src/single-core-regen/util/dataset.py
deleted file mode 100644
index 9537b80..0000000
--- a/src/single-core-regen/util/dataset.py
+++ /dev/null
@@ -1,53 +0,0 @@
-from pathlib import Path
-import torch
-from torch.utils.data import Dataset
-import numpy as np
-import configparser
-
-class SlicedDataset(Dataset):
-    def __init__(self, config_path, symbols, drop_first=0):
-        """
-        Initialize the dataset.
-
-        :param config_path: Path to the configuration file
-        :type config_path: str
-        :param out_size: Output size in symbols
-        :type out_size: int
-        :param reduce: Reduce the dataset size by taking every reduce-th sample
-        :type reduce: int
-        """
-
-        self.config = configparser.ConfigParser()
-        self.config.read(Path(config_path))
-        
-        self.data_path = (Path(self.config['data']['dir'].strip('"')) / (self.config['data']['npy_dir'].strip('"')) / self.config['data']['file'].strip('"'))
-        
-        self.symbols_per_slice = symbols
-        self.samples_per_symbol = int(self.config['glova']['sps'])
-        self.samples_per_slice = self.symbols_per_slice * self.samples_per_symbol
-        
-        data_raw = torch.tensor(np.load(self.data_path))[drop_first*self.samples_per_symbol:]
-        data_raw = data_raw.transpose(0,1)
-        data_raw = data_raw.view(2,2,-1)
-        # [no_samples, 4] -> [4, no_samples] -> [2, 2, no_samples]
-        
-        self.data = data_raw.unfold(dimension=-1, size=self.samples_per_slice, step=1)
-        self.data = self.data.movedim(-2, 0)
-        # -> [no_slices, 2, 2, samples_per_slice]
-        ...
-
-
-    def __len__(self):
-        return self.data.shape[0]
-    
-    def __getitem__(self, idx):
-        if isinstance(idx, slice):
-            return [self.__getitem__(i) for i in range(*idx.indices(len(self)))]
-        else:
-            return (self.data[idx,1].squeeze(), self.data[idx,0].squeeze())
-    
-
-if __name__ == "__main__":
-    
-
-    pass
\ No newline at end of file
diff --git a/src/single-core-regen/util/datasets.py b/src/single-core-regen/util/datasets.py
new file mode 100644
index 0000000..7bbdec5
--- /dev/null
+++ b/src/single-core-regen/util/datasets.py
@@ -0,0 +1,256 @@
+from pathlib import Path
+import torch
+from torch.utils.data import Dataset
+import numpy as np
+import configparser
+
+
+def load_data(config_path, skipfirst=0, num_symbols=None):
+    filepath = Path(config_path)
+    filepath = filepath.parent.glob(filepath.name)
+    config = configparser.ConfigParser()
+    config.read(filepath)
+    path_elements = (
+        config["data"]["dir"],
+        config["data"]["npy_dir"],
+        config["data"]["file"],
+    )
+    datapath = Path("/".join(path_elements).replace('"', ""))
+    sps = int(config["glova"]["sps"])
+
+    if num_symbols is None:
+        num_symbols = int(config["glova"]["nos"]) - skipfirst
+
+    data = np.load(datapath)[skipfirst * sps : num_symbols * sps + skipfirst * sps]
+    config["glova"]["nos"] = str(num_symbols)
+
+    return data, config
+
+
+def roll_along(arr, shifts, dim):
+    # https://stackoverflow.com/a/76920720
+    # (c) Mateen Ulhaq, 2023
+    # CC BY-SA 4.0
+    shifts = torch.tensor(shifts)
+    assert arr.ndim - 1 == shifts.ndim
+    dim %= arr.ndim
+    shape = (1,) * dim + (-1,) + (1,) * (arr.ndim - dim - 1)
+    dim_indices = torch.arange(arr.shape[dim]).reshape(shape)
+    indices = (dim_indices - shifts.unsqueeze(dim)) % arr.shape[dim]
+    return torch.gather(arr, dim, indices)
+
+
+class FiberRegenerationDataset(Dataset):
+    """
+    Dataset for fiber regeneration training.
+
+    The dataset is loaded from a configuration file, which must contain (at least) the following sections:
+    ```
+    [data]
+    dir = <data_dir>
+    npy_dir = <npy_dir>
+    file = <data_file>
+
+    [glova]
+    sps = <samples per symbol>
+    ```
+    The data is loaded from the file `<data_dir>/<npy_dir>/<data_file>` and is assumed to be in the following format:
+    ```
+    [ E_in_x,
+      E_in_y,
+      E_out_x,
+      E_out_y ]
+    ```
+
+    The dataset is sliced into slices, where each slice consists of a (fractional) number of symbols.
+    The target can be delayed relative to the input data by a (fractional) number of symbols.
+    The x and y channels can be delayed relative to each other by a (fractional) number of symbols.
+    """
+
+    def __init__(
+        self,
+        file_path: str | Path,
+        symbols: int | float,
+        *,
+        data_size: int = None,
+        target_delay: float | int = 0,
+        xy_delay: float | int = 0,
+        drop_first: float | int = 0,
+        **kwargs,
+    ):
+        """
+        Initialize the dataset.
+
+        :param file_path: Path to the data file. Can contain wildcards (*). The first
+        :type file_path: str | pathlib.Path
+        :param symbols: Number of symbols in each slice. Can be a float to specify a fraction of a symbol.
+        :type symbols: float | int
+        :param data_size: Number of samples in each slice. The data is reduced by taking equally spaced samples. If unset, each slice will contain symbols*samples_per_symbol samples.
+        :type data_size: int, optional
+        :param target_delay: Delay (in fractional symbols) between data and target. A positive delay means the target is delayed relative to the data. Default is 0.
+        :type target_delay: float | int, optional
+        :param xy_delay: Delay (in fractional symbols) between the x and y channels. A positive delay means the y channel is delayed relative to the x channel. Default is 0.
+        :type xy_delay: float | int, optional
+        :param drop_first: Number of (fractional) symbols to drop from the beginning
+        :type drop_first: float | int
+        """
+
+        # check types
+        assert isinstance(file_path, str), "file_path must be a string"
+        assert isinstance(symbols, (float, int)), (
+            "symbols must be a float or an integer"
+        )
+        assert data_size is None or isinstance(data_size, int), (
+            "output_len must be an integer"
+        )
+        assert isinstance(target_delay, (float, int)), (
+            "target_delay must be a float or an integer"
+        )
+        assert isinstance(xy_delay, (float, int)), (
+            "xy_delay must be a float or an integer"
+        )
+        assert isinstance(drop_first, int), "drop_first must be an integer"
+
+        # check values
+        assert symbols > 0, "symbols must be positive"
+        assert data_size is None or data_size > 0, "output_len must be positive or None"
+        assert drop_first >= 0, "drop_first must be non-negative"
+
+        faux = kwargs.pop("faux", False)
+
+        if faux:
+            data_raw = np.array(
+                [[i + 0.1j, i + 0.2j, i + 1.1j, i + 1.2j] for i in range(12800)],
+                dtype=np.complex128,
+            )
+            self.config = {
+                "data": {"dir": '"."', "npy_dir": '"."', "file": "faux"},
+                "glova": {"sps": 128},
+            }
+        else:
+            data_raw, self.config = load_data(file_path)
+
+        self.samples_per_symbol = int(self.config["glova"]["sps"])
+        self.samples_per_slice = int(symbols * self.samples_per_symbol)
+        self.symbols_per_slice = self.samples_per_slice / self.samples_per_symbol
+
+        self.data_size = data_size or self.samples_per_slice
+        self.target_delay = target_delay or 0
+        self.xy_delay = xy_delay or 0
+
+        ovrd_target_delay_samples = kwargs.pop("ovrd_target_delay_samples", None)
+        ovrd_xy_delay_samples = kwargs.pop("ovrd_xy_delay_samples", None)
+        ovrd_drop_first_samples = kwargs.pop("ovrd_drop_first_samples", None)
+
+        self.target_delay_samples = (
+            ovrd_target_delay_samples
+            if ovrd_target_delay_samples is not None
+            else int(self.target_delay * self.samples_per_symbol)
+        )
+        self.xy_delay_samples = (
+            ovrd_xy_delay_samples
+            if ovrd_xy_delay_samples is not None
+            else int(self.xy_delay * self.samples_per_symbol)
+        )
+        drop_first_samples = (
+            ovrd_drop_first_samples
+            if ovrd_drop_first_samples is not None
+            else int(drop_first * self.samples_per_symbol)
+        )
+
+        # drop samples from the beginning
+        data_raw = data_raw[drop_first_samples:]
+
+        # data layout
+        # [ [E_in_x0, E_in_y0, E_out_x0, E_out_y0],
+        #   [E_in_x1, E_in_y1, E_out_x1, E_out_y1],
+        #        ... 
+        #   [E_in_xN, E_in_yN, E_out_xN, E_out_yN] ]
+
+        data_raw = data_raw.transpose(0, 1)
+
+        # data layout
+        # [  E_in_x[0:N],  
+        #    E_in_y[0:N],  
+        #   E_out_x[0:N], 
+        #   E_out_y[0:N] ]
+
+        # shift x data by xy_delay_samples relative to the y data (example value: 3)
+        # [ E_in_x [0:N],         [ E_in_x [ 0:N  ],        [ E_in_x [3:N  ],
+        #   E_in_y [0:N],    ->     E_in_y [-3:N-3],    ->    E_in_y [0:N-3],
+        #   E_out_x[0:N],           E_out_x[ 0:N  ],          E_out_x[3:N  ],
+        #   E_out_y[0:N] ]          E_out_y[-3:N-3] ]         E_out_y[0:N-3] ]
+
+        if self.xy_delay_samples != 0:
+            data_raw = roll_along(
+                data_raw, [0, self.xy_delay_samples, 0, self.xy_delay_samples], dim=1
+            )
+        if self.xy_delay_samples > 0:
+            data_raw = data_raw[:, self.xy_delay_samples :]
+        elif self.xy_delay_samples < 0:
+            data_raw = data_raw[:, : self.xy_delay_samples]
+
+        # shift fiber input data (target) by target_delay_samples relative to the fiber output data (input)
+        # (example value: 5)
+        # [ E_in_x [0:N],         [ E_in_x [-5:N-5],        [ E_in_x [0:N-5],
+        #   E_in_y [0:N],    ->     E_in_y [-5:N-5],    ->    E_in_y [0:N-5],
+        #   E_out_x[0:N],           E_out_x[ 0:N  ],          E_out_x[5:N  ],
+        #   E_out_y[0:N] ]          E_out_y[ 0:N  ] ]         E_out_y[5:N  ] ]
+
+        if self.target_delay_samples != 0:
+            data_raw = roll_along(
+                data_raw,
+                [self.target_delay_samples, self.target_delay_samples, 0, 0],
+                dim=1,
+            )
+        if self.target_delay_samples > 0:
+            data_raw = data_raw[:, self.target_delay_samples :]
+        elif self.target_delay_samples < 0:
+            data_raw = data_raw[:, : self.target_delay_samples]
+
+        data_raw = data_raw.view(2, 2, -1)
+        # data layout
+        # [ [E_in_x,  E_in_y],
+        #   [E_out_x, E_out_y] ]
+
+        self.data = data_raw.unfold(dimension=-1, size=self.samples_per_slice, step=1)
+        self.data = self.data.movedim(-2, 0)
+        # -> [no_slices, 2, 2, samples_per_slice]
+
+        # data layout
+        # [
+        #   [ [E_in_x[0:N+0], E_in_y[0:N+0] ], [ E_out_x[0:N+0], E_out_y[0:N+0] ] ],
+        #   [ [E_in_x[1:N+1], E_in_y[1:N+1] ], [ E_out_x[1:N+1], E_out_y[1:N+1] ] ],
+        #   ...
+        # ] -> [no_slices, 2, 2, samples_per_slice]
+
+        ...
+
+    def __len__(self):
+        return self.data.shape[0]
+
+    def __getitem__(self, idx):
+        if isinstance(idx, slice):
+            return [self.__getitem__(i) for i in range(*idx.indices(len(self)))]
+        else:
+            data, target = self.data[idx, 1].squeeze(), self.data[idx, 0].squeeze()
+
+            # reduce by by taking self.output_dim equally spaced samples
+            data = data[:, : data.shape[1] // self.data_size * self.data_size]
+            data = data.view(data.shape[0], self.data_size, -1)
+            data = data[:, :, 0]
+
+            # target is corresponding to the latest data point -> try to regenerate that
+            target = target[:, : target.shape[1] // self.data_size * self.data_size]
+            target = target.view(target.shape[0], self.data_size, -1)
+            target = target[:, 0, 0]
+
+            data = data.transpose(0, 1).flatten().squeeze()
+            target = target.flatten().squeeze()
+
+            # data layout:
+            # [sample_x0, sample_y0, sample_x1, sample_y1, ...]
+            # target layout:
+            # [sample_x0, sample_y0]
+
+            return data, target
diff --git a/src/single-core-regen/util/plot.py b/src/single-core-regen/util/plot.py
new file mode 100644
index 0000000..8a3a196
--- /dev/null
+++ b/src/single-core-regen/util/plot.py
@@ -0,0 +1,34 @@
+import matplotlib.pyplot as plt
+import numpy as np
+from .datasets import load_data
+
+def eye(path, title=None, head=1000, skipfirst=1000, show=True):
+    """Plot an eye diagram for the data given by filepath.
+    
+    Args:
+        path (str): Path to the data description file.
+        title (str): Title of the plot.
+        head (int): Number of symbols to plot.
+        skipfirst (int): Number of symbols to skip.
+        show (bool): Whether to call plt.show().
+    """
+    data, config = load_data(path, skipfirst, head)
+    sps = int(config["glova"]["sps"])
+
+    xaxis = np.linspace(0, 2, 2*sps, endpoint=False)
+    fig, axs = plt.subplots(2, 2, figsize=(10, 10), sharex=True, sharey=True)
+    for i in range(head-1):
+        inx, iny, outx, outy = data[i*sps:(i+2)*sps].T
+        axs[0, 0].plot(xaxis, np.abs(inx)**2, color="C0", alpha=0.1)
+        axs[0, 1].plot(xaxis, np.abs(outx)**2, color="C0", alpha=0.1)
+        axs[1, 0].plot(xaxis, np.abs(iny)**2, color="C0", alpha=0.1)
+        axs[1, 1].plot(xaxis, np.abs(outy)**2, color="C0", alpha=0.1)
+    
+    axs[0, 0].set_title("Input x")
+    axs[0, 1].set_title("Output x")
+    axs[1, 0].set_title("Input y")
+    axs[1, 1].set_title("Output y")
+    fig.suptitle(title)
+
+    if show:
+        plt.show(block=False)