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pytorch-ts/pts/feature/fourier_date_feature.py
2021-02-21 11:49:56 +01:00

71 lines
2.1 KiB
Python

# Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License").
# You may not use this file except in compliance with the License.
# A copy of the License is located at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# or in the "license" file accompanying this file. This file is distributed
# on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
# express or implied. See the License for the specific language governing
# permissions and limitations under the License.
from typing import List
import numpy as np
import pandas as pd
from pandas.tseries.frequencies import to_offset
from gluonts.core.component import validated
from gluonts.time_feature import TimeFeature, norm_freq_str
class FourierDateFeatures(TimeFeature):
@validated()
def __init__(self, freq: str) -> None:
super().__init__()
# reocurring freq
freqs = [
"month",
"day",
"hour",
"minute",
"weekofyear",
"weekday",
"dayofweek",
"dayofyear",
"daysinmonth",
]
assert freq in freqs
self.freq = freq
def __call__(self, index: pd.DatetimeIndex) -> np.ndarray:
values = getattr(index, self.freq)
num_values = max(values) + 1
steps = [x * 2.0 * np.pi / num_values for x in values]
return np.vstack([np.cos(steps), np.sin(steps)])
def fourier_time_features_from_frequency(freq_str: str) -> List[TimeFeature]:
offset = to_offset(freq_str)
granularity = norm_freq_str(offset.name)
features = {
"M": ["weekofyear"],
"W": ["daysinmonth", "weekofyear"],
"D": ["dayofweek"],
"B": ["dayofweek", "dayofyear"],
"H": ["hour", "dayofweek"],
"min": ["minute", "hour", "dayofweek"],
"T": ["minute", "hour", "dayofweek"],
}
assert granularity in features, f"freq {granularity} not supported"
feature_classes: List[TimeFeature] = [
FourierDateFeatures(freq=freq) for freq in features[granularity]
]
return feature_classes