trender.py

import numpy
import pandas


def trend_line(index, data, order=1):
    coefficients = numpy.polyfit(index, list(data), order)
    slope = coefficients[-2]
    return float(slope)


def get_trend(price_list):
    data = {"prices": price_list}
    df = pandas.DataFrame(data)

    rolling_averages = df.rolling(window=2).mean()
    trend_averages = [x[0] for x in rolling_averages.values][1:]

    index = range(1, len(trend_averages) + 1)
    resultant = trend_line(index, trend_averages)

    print(resultant)
    if resultant < -0.1:
        return "Downward Trend"
    if -0.1 < resultant < 0.1:
        return "No Trend"
    if 0.1 < resultant:
        return "Upward Trend"


if __name__ == "__main__":
    print(get_trend([11.30, 12.0, 12.0, 11.80, 12.40]))
    print(get_trend([10.00, 9.99, 9.99, 10.00, 10.00, 9.99, 9.87]))