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1. Auxiliary functions

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FlattenHead

 FlattenHead (n_vars, nf, target_window, head_dropout=0)
*Base class for all neural network modules. Your models should also subclass this class. Modules can also contain other Modules, allowing them to be nested in a tree structure. You can assign the submodules as regular attributes:: 
import torch.nn as nn
import torch.nn.functional as F

class Model(nn.Module):
    def __init__(self) -> None:
        super().__init__()
        self.conv1 = nn.Conv2d(1, 20, 5)
        self.conv2 = nn.Conv2d(20, 20, 5)

    def forward(self, x):
        x = F.relu(self.conv1(x))
        return F.relu(self.conv2(x))
Submodules assigned in this way will be registered, and will also have their parameters converted when you call :meth:to, etc. .. note:: As per the example above, an __init__() call to the parent class must be made before assignment on the child. :ivar training: Boolean represents whether this module is in training or evaluation mode. :vartype training: bool*
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Encoder

 Encoder (layers, norm_layer=None, projection=None)
*Base class for all neural network modules. Your models should also subclass this class. Modules can also contain other Modules, allowing them to be nested in a tree structure. You can assign the submodules as regular attributes:: 
import torch.nn as nn
import torch.nn.functional as F

class Model(nn.Module):
    def __init__(self) -> None:
        super().__init__()
        self.conv1 = nn.Conv2d(1, 20, 5)
        self.conv2 = nn.Conv2d(20, 20, 5)

    def forward(self, x):
        x = F.relu(self.conv1(x))
        return F.relu(self.conv2(x))
Submodules assigned in this way will be registered, and will also have their parameters converted when you call :meth:to, etc. .. note:: As per the example above, an __init__() call to the parent class must be made before assignment on the child. :ivar training: Boolean represents whether this module is in training or evaluation mode. :vartype training: bool*
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EncoderLayer

 EncoderLayer (self_attention, cross_attention, d_model, d_ff=None,
               dropout=0.1, activation='relu')
*Base class for all neural network modules. Your models should also subclass this class. Modules can also contain other Modules, allowing them to be nested in a tree structure. You can assign the submodules as regular attributes:: 
import torch.nn as nn
import torch.nn.functional as F

class Model(nn.Module):
    def __init__(self) -> None:
        super().__init__()
        self.conv1 = nn.Conv2d(1, 20, 5)
        self.conv2 = nn.Conv2d(20, 20, 5)

    def forward(self, x):
        x = F.relu(self.conv1(x))
        return F.relu(self.conv2(x))
Submodules assigned in this way will be registered, and will also have their parameters converted when you call :meth:to, etc. .. note:: As per the example above, an __init__() call to the parent class must be made before assignment on the child. :ivar training: Boolean represents whether this module is in training or evaluation mode. :vartype training: bool*
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EnEmbedding

 EnEmbedding (n_vars, d_model, patch_len, dropout)
*Base class for all neural network modules. Your models should also subclass this class. Modules can also contain other Modules, allowing them to be nested in a tree structure. You can assign the submodules as regular attributes:: 
import torch.nn as nn
import torch.nn.functional as F

class Model(nn.Module):
    def __init__(self) -> None:
        super().__init__()
        self.conv1 = nn.Conv2d(1, 20, 5)
        self.conv2 = nn.Conv2d(20, 20, 5)

    def forward(self, x):
        x = F.relu(self.conv1(x))
        return F.relu(self.conv2(x))
Submodules assigned in this way will be registered, and will also have their parameters converted when you call :meth:to, etc. .. note:: As per the example above, an __init__() call to the parent class must be made before assignment on the child. :ivar training: Boolean represents whether this module is in training or evaluation mode. :vartype training: bool*

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2. Model

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TimeXer

 TimeXer (h, input_size, n_series, futr_exog_list=None,
          hist_exog_list=None, stat_exog_list=None,
          exclude_insample_y:bool=False, patch_len:int=16,
          hidden_size:int=512, n_heads:int=8, e_layers:int=2,
          d_ff:int=2048, factor:int=1, dropout:float=0.1,
          use_norm:bool=True, loss=MAE(), valid_loss=None,
          max_steps:int=1000, learning_rate:float=0.001,
          num_lr_decays:int=-1, early_stop_patience_steps:int=-1,
          val_check_steps:int=100, batch_size:int=32,
          valid_batch_size:Optional[int]=None, windows_batch_size=32,
          inference_windows_batch_size=32, start_padding_enabled=False,
          step_size:int=1, scaler_type:str='identity', random_seed:int=1,
          drop_last_loader:bool=False, alias:Optional[str]=None,
          optimizer=None, optimizer_kwargs=None, lr_scheduler=None,
          lr_scheduler_kwargs=None, dataloader_kwargs=None,
          **trainer_kwargs)
*TimeXer Parameters:
h: int, Forecast horizon.
input_size: int, autorregresive inputs size, y=[1,2,3,4] input_size=2 -> y_[t-2:t]=[1,2].
n_series: int, number of time-series.
futr_exog_list: str list, future exogenous columns.
hist_exog_list: str list, historic exogenous columns.
stat_exog_list: str list, static exogenous columns.
patch_len: int, length of patches.
hidden_size: int, dimension of the model.
n_heads: int, number of heads.
e_layers: int, number of encoder layers.
d_ff: int, dimension of fully-connected layer.
factor: int, attention factor.
dropout: float, dropout rate.
use_norm: bool, whether to normalize or not.
loss: PyTorch module, instantiated train loss class from losses collection.
valid_loss: PyTorch module=loss, instantiated valid loss class from losses collection.
max_steps: int=1000, maximum number of training steps.
learning_rate: float=1e-3, Learning rate between (0, 1).
num_lr_decays: int=-1, Number of learning rate decays, evenly distributed across max_steps.
early_stop_patience_steps: int=-1, Number of validation iterations before early stopping.
val_check_steps: int=100, Number of training steps between every validation loss check.
batch_size: int=32, number of different series in each batch.
valid_batch_size: int=None, number of different series in each validation and test batch, if None uses batch_size.
windows_batch_size: int=32, number of windows in each batch.

inference_windows_batch_size: int=32, number of windows to sample in each inference batch, -1 uses all.
start_padding_enabled: bool=False, if True, the model will pad the time series with zeros at the beginning, by input size.
step_size: int=1, step size between each window of temporal data.
scaler_type: str=‘identity’, type of scaler for temporal inputs normalization see temporal scalers.
random_seed: int=1, random_seed for pytorch initializer and numpy generators.
drop_last_loader: bool=False, if True TimeSeriesDataLoader drops last non-full batch.
alias: str, optional, Custom name of the model.
optimizer: Subclass of ‘torch.optim.Optimizer’, optional, user specified optimizer instead of the default choice (Adam).
optimizer_kwargs: dict, optional, list of parameters used by the user specified optimizer.
lr_scheduler: Subclass of ‘torch.optim.lr_scheduler.LRScheduler’, optional, user specified lr_scheduler instead of the default choice (StepLR).
lr_scheduler_kwargs: dict, optional, list of parameters used by the user specified lr_scheduler.
dataloader_kwargs: dict, optional, list of parameters passed into the PyTorch Lightning dataloader by the TimeSeriesDataLoader.
**trainer_kwargs: int, keyword trainer arguments inherited from PyTorch Lighning’s trainer.
 Parameters:
 References - Yuxuan Wang, Haixu Wu, Jiaxiang Dong, Guo Qin, Haoran Zhang, Yong Liu, Yunzhong Qiu, Jianmin Wang, Mingsheng Long. “TimeXer: Empowering Transformers for Time Series Forecasting with Exogenous Variables”*

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TimeXer.fit

 TimeXer.fit (dataset, val_size=0, test_size=0, random_seed=None,
              distributed_config=None)
*Fit. The fit method, optimizes the neural network’s weights using the initialization parameters (learning_rate, windows_batch_size, …) and the loss function as defined during the initialization. Within fit we use a PyTorch Lightning Trainer that inherits the initialization’s self.trainer_kwargs, to customize its inputs, see PL’s trainer arguments. The method is designed to be compatible with SKLearn-like classes and in particular to be compatible with the StatsForecast library. By default the model is not saving training checkpoints to protect disk memory, to get them change enable_checkpointing=True in __init__. Parameters:
dataset: NeuralForecast’s TimeSeriesDataset, see documentation.
val_size: int, validation size for temporal cross-validation.
random_seed: int=None, random_seed for pytorch initializer and numpy generators, overwrites model.__init__’s.
test_size: int, test size for temporal cross-validation.
*

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TimeXer.predict

 TimeXer.predict (dataset, test_size=None, step_size=1, random_seed=None,
                  quantiles=None, **data_module_kwargs)
*Predict. Neural network prediction with PL’s Trainer execution of predict_step. Parameters:
dataset: NeuralForecast’s TimeSeriesDataset, see documentation.
test_size: int=None, test size for temporal cross-validation.
step_size: int=1, Step size between each window.
random_seed: int=None, random_seed for pytorch initializer and numpy generators, overwrites model.__init__’s.
quantiles: list of floats, optional (default=None), target quantiles to predict.
**data_module_kwargs: PL’s TimeSeriesDataModule args, see documentation.* 
# Unit tests for models
logging.getLogger("pytorch_lightning").setLevel(logging.ERROR)
logging.getLogger("lightning_fabric").setLevel(logging.ERROR)
with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    check_model(TimeXer, ["airpassengers"])

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3. Usage example

import pandas as pd
import matplotlib.pyplot as plt

from neuralforecast import NeuralForecast
from neuralforecast.models import TimeXer
from neuralforecast.losses.pytorch import MSE
from neuralforecast.utils import AirPassengersPanel, AirPassengersStatic, augment_calendar_df

AirPassengersPanel, calendar_cols = augment_calendar_df(df=AirPassengersPanel, freq='M')

Y_train_df = AirPassengersPanel[AirPassengersPanel.ds<AirPassengersPanel['ds'].values[-12]] # 132 train
Y_test_df = AirPassengersPanel[AirPassengersPanel.ds>=AirPassengersPanel['ds'].values[-12]].reset_index(drop=True) # 12 test

model = TimeXer(h=12,
                input_size=24,
                n_series=2,
                futr_exog_list=["trend", "month"],
                patch_len=12,
                hidden_size=128,
                n_heads=16,
                e_layers=2,
                d_ff=256,
                factor=1,
                dropout=0.1,
                use_norm=True,
                loss=MSE(),
                valid_loss=MAE(),
                early_stop_patience_steps=3,
                batch_size=32)

fcst = NeuralForecast(models=[model], freq='ME')
fcst.fit(df=Y_train_df, static_df=AirPassengersStatic, val_size=12)
forecasts = fcst.predict(futr_df=Y_test_df)

# Plot predictions
fig, ax = plt.subplots(1, 1, figsize = (20, 7))
Y_hat_df = forecasts.reset_index(drop=False).drop(columns=['unique_id','ds'])
plot_df = pd.concat([Y_test_df, Y_hat_df], axis=1)
plot_df = pd.concat([Y_train_df, plot_df])

plot_df = plot_df[plot_df.unique_id=='Airline1'].drop('unique_id', axis=1)
plt.plot(plot_df['ds'], plot_df['y'], c='black', label='True')
plt.plot(plot_df['ds'], plot_df['TimeXer'], c='blue', label='Forecast')
ax.set_title('AirPassengers Forecast', fontsize=22)
ax.set_ylabel('Monthly Passengers', fontsize=20)
ax.set_xlabel('Year', fontsize=20)
ax.legend(prop={'size': 15})
ax.grid()