stable/freqtrade/indicator_helpers.py

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2018-02-13 15:47:26 +00:00
from math import exp, pi, sqrt, cos
import numpy
import talib as ta
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from pandas import Series
def went_up(series: Series) -> Series:
return series > series.shift(1)
def went_down(series: Series) -> Series:
return series < series.shift(1)
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def ehlers_super_smoother(series: Series, smoothing: float = 6):
magic = pi * sqrt(2) / smoothing
a1 = exp(-magic)
coeff2 = 2 * a1 * cos(magic)
coeff3 = -a1 * a1
coeff1 = (1 - coeff2 - coeff3) / 2
filtered = series.copy()
for i in range(2, len(series)):
filtered.iloc[i] = coeff1 * (series.iloc[i] + series.iloc[i-1]) + \
coeff2 * filtered.iloc[i-1] + coeff3 * filtered.iloc[i-2]
return filtered
def fishers_inverse(series: Series, smoothing: float = 0):
""" Does a smoothed fishers inverse transformation.
Can be used with any oscillator that goes from 0 to 100 like RSI or MFI """
v1 = 0.1 * (series - 50)
if smoothing > 0:
v2 = ta.WMA(v1.values, timeperiod=smoothing)
else:
v2 = v1
return (numpy.exp(2 * v2)-1) / (numpy.exp(2 * v2) + 1)