Trend indicator sample

obv.py

import matplotlib.pyplot as plt

def OBV(df):
    df["obv"] = np.where(df['Close'] > df['Close'].shift(1), df['Volume'], 
                         np.where(df['Close'] < df['Close'].shift(1), -df['Volume'], 0)).cumsum()
    xdate = [x.date() for x in df.index]
    plt.figure(figsize=(15, 10))
    
    # plot the original closing line
    plt.subplot(211)
    plt.plot(xdate, df.Close, label="close")
    plt.xlim(xdate[0], xdate[-1])
    plt.legend()
    plt.grid()
    
    # plot volume and OBV
    plt.subplot(212)
    plt.title("OBV")
    # plt.bar(xdate, df.Volume, label="volume")
    plt.plot(xdate, df.obv, label="obv")
    plt.xlim(xdate[0], xdate[-1])
    plt.legend()
    plt.grid(True)