StemGNN
The Spectral Temporal Graph Neural Network
(StemGNN
)
is a Graph-based multivariate time-series forecasting model.
StemGNN
jointly learns temporal dependencies and inter-series correlations in
the spectral domain, by combining Graph Fourier Transform (GFT) and
Discrete Fourier Transform (DFT).
This method proved state-of-the-art performance on geo-temporal datasets
such as Solar
, METR-LA
, and PEMS-BAY
, and
source
GLU
GLU (input_channel, output_channel)
*Base class for all neural network modules.
Your models should also subclass this class.
Modules can also contain other Modules, allowing to nest them 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):
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 have their
parameters converted too 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*
source
StockBlockLayer
StockBlockLayer (time_step, unit, multi_layer, stack_cnt=0)
*Base class for all neural network modules.
Your models should also subclass this class.
Modules can also contain other Modules, allowing to nest them 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):
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 have their
parameters converted too 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*
source
StemGNN
StemGNN (h, input_size, n_series, futr_exog_list=None, hist_exog_list=None, stat_exog_list=None, n_stacks=2, multi_layer:int=5, dropout_rate:float=0.5, leaky_rate:float=0.2, loss=MAE(), valid_loss=None, max_steps:int=1000, learning_rate:float=0.001, num_lr_decays:int=3, early_stop_patience_steps:int=-1, val_check_steps:int=100, batch_size:int=32, step_size:int=1, scaler_type:str='robust', random_seed:int=1, num_workers_loader=0, drop_last_loader=False, optimizer=None, optimizer_kwargs=None, **trainer_kwargs)
*StemGNN
The Spectral Temporal Graph Neural Network
(StemGNN
)
is a Graph-based multivariate time-series forecasting model.
StemGNN
jointly learns temporal dependencies and inter-series correlations in
the spectral domain, by combining Graph Fourier Transform (GFT) and
Discrete Fourier Transform (DFT).
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.
stat_exog_list
: str list, static exogenous columns.
hist_exog_list
: str list, historic exogenous columns.
futr_exog_list
: str list, future exogenous columns.
n_stacks
:
int=2, number of stacks in the model.
multi_layer
: int=5,
multiplier for FC hidden size on StemGNN blocks.
dropout_rate
:
float=0.5, dropout rate.
leaky_rate
: float=0.2, alpha for
LeakyReLU layer on Latent Correlation layer.
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, number of windows in each
batch.
step_size
: int=1, step size between each window of temporal
data.
scaler_type
: str=‘robust’, type of scaler for temporal
inputs normalization see temporal
scalers.
random_seed
: int, random_seed for pytorch initializer and numpy
generators.
num_workers_loader
: int=os.cpu_count(), workers to be
used by TimeSeriesDataLoader
.
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
.
**trainer_kwargs
: int, keyword trainer arguments inherited from
PyTorch Lighning’s
trainer.
*
StemGNN.fit
StemGNN.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.
test_size
: int, test size for temporal cross-validation.
*
StemGNN.predict
StemGNN.predict (dataset, test_size=None, step_size=1, random_seed=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.
**data_module_kwargs
: PL’s TimeSeriesDataModule args, see
documentation.*
Usage Examples
Train model and forecast future values with predict
method.
import numpy as np
import pandas as pd
import pytorch_lightning as pl
import matplotlib.pyplot as plt
from neuralforecast import NeuralForecast
from neuralforecast.utils import AirPassengersPanel, AirPassengersStatic
from neuralforecast.losses.pytorch import MAE
Y_train_df = AirPassengersPanel[AirPassengersPanel.ds<AirPassengersPanel['ds'].values[-12]].reset_index(drop=True) # 132 train
Y_test_df = AirPassengersPanel[AirPassengersPanel.ds>=AirPassengersPanel['ds'].values[-12]].reset_index(drop=True) # 12 test
model = StemGNN(h=12,
input_size=24,
n_series=2,
stat_exog_list=['airline1'],
futr_exog_list=['trend'],
scaler_type='robust',
max_steps=500,
early_stop_patience_steps=-1,
val_check_steps=10,
learning_rate=1e-3,
loss=MAE(),
valid_loss=None,
batch_size=32
)
fcst = NeuralForecast(models=[model], freq='M')
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['StemGNN'], 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()
Using cross_validation
to forecast multiple historic values.
fcst = NeuralForecast(models=[model], freq='M')
forecasts = fcst.cross_validation(df=AirPassengersPanel, static_df=AirPassengersStatic, n_windows=2, step_size=12)
# Plot predictions
fig, ax = plt.subplots(1, 1, figsize = (20, 7))
Y_hat_df = forecasts.loc['Airline1']
Y_df = AirPassengersPanel[AirPassengersPanel['unique_id']=='Airline1']
plt.plot(Y_df['ds'], Y_df['y'], c='black', label='True')
plt.plot(Y_hat_df['ds'], Y_hat_df['StemGNN'], 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()