TimeMixer
Embedding
source
DataEmbedding_wo_pos
DataEmbedding_wo_pos
DFT decomposition
source
DFT_series_decomp
Series decomposition block
Mixing
source
PastDecomposableMixing
PastDecomposableMixing
source
MultiScaleTrendMixing
Top-down mixing trend pattern
source
MultiScaleSeasonMixing
Bottom-up mixing season pattern
2. Model
source
TimeMixer
*TimeMixer 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.
d_model
:
int, dimension of the model.
d_ff
: int, dimension of the
fully-connected network.
dropout
: float, dropout rate.
e_layers
: int, number of encoder layers.
top_k
: int, number of
selected frequencies.
decomp_method
: str, method of series
decomposition [moving_avg, dft_decomp].
moving_avg
: int, window
size of moving average.
channel_independence
: int, 0: channel
dependence, 1: channel independence.
down_sampling_layers
: int,
number of downsampling layers.
down_sampling_window
: int, size of
downsampling window.
down_sampling_method
: str, down sampling
method [avg, max, conv].
use_norm
: bool, whether to normalize or
not.
decoder_input_size_multiplier
: float = 0.5.
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.
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.
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
.
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.
TimeMixer.fit
*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.
*
TimeMixer.predict
*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.*
3. Usage example
Using cross_validation
to forecast multiple historic values.