indicator.py

import pandas as pd
import numpy as np
from pandas import DataFrame, Series


def sma(ohlc: DataFrame, period=9) -> Series:
    return Series(
        ohlc['close'].rolling(period).mean(),
        name=f'SMA {period}',
    )

def ema(ohlc: DataFrame, period=9) -> Series:
    return Series(
        ohlc['close'].ewm(span=period).mean(),
        name=f'EMA {period}',
    )

def wma(ohlc: DataFrame, period=9) -> Series:
    # WMA = ( 価格 * n + 価格(1) * n-1 + ... 価格(n-1) * 1) / ( n * (n+1) / 2 )
    denominator = (period * (period + 1)) / 2
    weights = Series(np.arange(1, period + 1)).iloc[::-1]

    return Series(
        ohlc['close'].rolling(period, min_periods=period).apply(lambda x: np.sum(weights * x) / denominator, raw=True),
        name=f'WMA {period}'
    )

def sd(ohlc: DataFrame, period=10, ddof=0) -> float:
    return ohlc['close'].tail(period).std(ddof=ddof)