BBWidthRatio.py

import pandas as pd
import talib

def bollinger_band_width_ratio(df, period=20, deviations=2.0):
    """
    Calculates the Bollinger Bands width ratio indicator.
    
    Args:
    df : pandas.DataFrame
        A DataFrame containing 'open', 'high', 'low', 'close', and 'volume' columns.
    period : int
        The number of periods to use when calculating the Bollinger Bands.
    deviations : float
        The number of standard deviations to use when calculating the Bollinger Bands width.
        
    Returns:
    pandas.Series
        A series containing the Bollinger Bands width ratio indicator values.
    """
    
    # Calculate Bollinger Bands
    upperband, middleband, lowerband = talib.BBANDS(
        df['close'], timeperiod=period, nbdevup=deviations, nbdevdn=deviations, matype=0)
    
    # Calculate the width of the bands as a ratio to the middle band
    bb_width_ratio = ((upperband - lowerband) / middleband) * 100
    
    return bb_width_ratio

# Example usage:
# Assuming 'data' is a pandas DataFrame with the required columns
# data['BBWidthRatio'] = bollinger_band_width_ratio(data, period=20, deviations=2.0)