Files
drift/training/walk_forward.py
T
Mark Aron Szulyovszky c611481eb6 refactor(WalkForward): separate train / test functions to help with inference later (#158)
* refactor(WalkForward): separate train / test functions (draft) to potentially help with inference later

* fix(Training): use the new separate train / test functions

* feat(Training): return and pass in scalers that are necessary for inference

* fix(Project): runtime errors

* fix(WalkForward): use the correct `train_from` value

* fix(Tests): for new walk_forward functions()

* refactor(WalkForward): rename `walk_forward_test()` to `walk_forward_inference()`
2022-01-12 14:42:16 +01:00

121 lines
4.5 KiB
Python

import pandas as pd
from models.base import Model
import numpy as np
from utils.helpers import get_first_valid_return_index
from tqdm import tqdm
from sklearn.preprocessing import MinMaxScaler, Normalizer, StandardScaler
from typing import Union
from sklearn.base import clone
def walk_forward_train(
model_name: str,
model: Model,
X: pd.DataFrame,
y: pd.Series,
target_returns: pd.Series,
expanding_window: bool,
window_size: int,
retrain_every: int,
scaler: Union[MinMaxScaler, Normalizer, StandardScaler],
) -> tuple[pd.Series, pd.Series]:
assert len(X) == len(y)
models = pd.Series(index=y.index).rename(model_name)
scalers = pd.Series(index=y.index).rename("scaler_" + model_name)
first_nonzero_return = max(get_first_valid_return_index(target_returns), get_first_valid_return_index(X.iloc[:,0]), get_first_valid_return_index(y))
train_from = first_nonzero_return + window_size + 1
train_till = len(y)
iterations_before_retrain = 0
if model.only_column is not None:
X = X[[column for column in X.columns if model.only_column in column]]
is_scaling_on = model.data_scaling == 'scaled'
if is_scaling_on:
scaler = clone(scaler)
for index in tqdm(range(train_from, train_till)):
if expanding_window:
train_window_start = first_nonzero_return
else:
train_window_start = index - window_size - 1
if iterations_before_retrain <= 0 or pd.isna(models[index-1]):
train_window_end = index - 1
current_scaler = None
if is_scaling_on:
# We need to fit on the expanding window data slice
# This is our only way to avoid lookahead bias
current_scaler = clone(scaler)
X_expanding_window = X[first_nonzero_return:train_window_end]
current_scaler.fit(X_expanding_window.values)
X_slice = X[train_window_start:train_window_end].to_numpy()
y_slice = y[train_window_start:train_window_end].to_numpy()
if is_scaling_on:
X_slice = current_scaler.transform(X_slice)
current_model = model.clone()
current_model.initialize_network(input_dim = len(X_slice[0]), output_dim=1)
current_model.fit(X_slice, y_slice)
iterations_before_retrain = retrain_every
models[index] = current_model
scalers[index] = current_scaler
iterations_before_retrain -= 1
return models, scalers
def walk_forward_inference(
model_name: str,
models: pd.Series,
scalers: pd.Series,
X: pd.DataFrame,
expanding_window: bool,
window_size: int,
) -> tuple[pd.Series, pd.DataFrame]:
predictions = pd.Series(index=X.index).rename(model_name)
probabilities = pd.DataFrame(index=X.index)
first_nonzero_return = get_first_valid_return_index(models)
train_from = first_nonzero_return
train_till = X.shape[0]
first_model = models[first_nonzero_return]
if first_model.only_column is not None:
X = X[[column for column in X.columns if first_model.only_column in column]]
is_scaling_on = first_model.data_scaling == 'scaled'
for index in tqdm(range(train_from, train_till)):
if expanding_window:
train_window_start = first_nonzero_return
else:
train_window_start = index - window_size - 1
current_model = models[index]
curren_scaler = scalers[index]
if current_model.predict_window_size == 'window_size':
next_timestep = X.iloc[train_window_start:index].to_numpy()#.reshape(1, -1)
else:
next_timestep = X.iloc[index].to_numpy().reshape(1, -1)
if is_scaling_on:
next_timestep = curren_scaler.transform(next_timestep)
prediction, probs = current_model.predict(next_timestep)
predictions[index] = prediction
if len(probabilities.columns) != len(probs):
probabilities = probabilities.reindex(columns = ["prob_" + str(num) for num in range(0, len(probs.T))])
probabilities.iloc[index] = probs
return predictions, probabilities