Trend indicator MAs

Financial Trading in Python

Chelsea Yang

Data Science Instructor

What are technical indicators?

Mathematical calculations based on historical market data
Assume the market is efficient and the price has incorporated all public information
Help traders to gain insight into past price patterns

Types of indicators

Trend indicators: measure the direction or strength of a trend
- Example: Moving averages (MA), Average Directional Movement Index (ADX)
Momentum indicators: measure the velocity of price movement
- Example: Relative Strength Index (RSI)
Volatility indicators: measure the magnitude of price deviations
- Example: Bollinger Bands

The TA-Lib package

TA-Lib : Technical Analysis Library

Includes 150+ technical indicator implementations

import talib

Moving average indicators

SMA: Simple Moving average
EMA: Exponential Moving Average

Characteristics:
- Move with the price
- Smooth out the data to better indicate the price direction

Simple Moving Average (SMA)

$ SMA = (P_1+P_2+...+P_n)/n $

# Calculate two SMAs
stock_data['SMA_short'] = talib.SMA(stock_data['Close'], timeperiod=10)
stock_data['SMA_long'] = talib.SMA(stock_data['Close'], timeperiod=50)

# Print the last five rows
print(stock_data.tail())

             Close  SMA_short  SMA_long
Date                                   
2020-11-24 1768.88    1758.77   1594.74
2020-11-25 1771.43    1760.65   1599.75
2020-11-27 1793.19    1764.98   1605.70
2020-11-30 1760.74    1763.35   1611.71
2020-12-01 1798.10    1765.02   1619.05

Plotting the SMA

import matplotlib.pyplot as plt

# Plot SMA with the price
plt.plot(stock_data['SMA_short'], 
         label='SMA_short')
plt.plot(stock_data['SMA_long'], 
         label='SMA_long')
plt.plot(stock_data['Close'], 
         label='Close')

# Customize and show the plot
plt.legend()
plt.title('SMAs')
plt.show()

SMAs plot

Exponential Moving Average (EMA)

$EMA_n = P_n \times multiplier + \text{previous EMA} \times (1-multiplier)$

$multiplier = 2 / (n + 1)$

# Calculate two EMAs
stock_data['EMA_short'] = talib.EMA(stock_data['Close'], timeperiod=10)
stock_data['EMA_long'] = talib.EMA(stock_data['Close'], timeperiod=50)
# Print the last five rows
print(stock_data.tail())

             Close  EMA_short  EMA_long
Date                                   
2020-11-24 1768.88    1748.65   1640.98
2020-11-25 1771.43    1752.79   1646.09
2020-11-27 1793.19    1760.13   1651.86
2020-11-30 1760.74    1760.24   1656.13
2020-12-01 1798.10    1767.13   1661.70

Plotting the EMA

import matplotlib.pyplot as plt
# Plot EMA with the price
plt.plot(stock_data['EMA_short'], 
         label='EMA_short')
plt.plot(stock_data['EMA_long'], 
         label='EMA_long')
plt.plot(stock_data['Close'], 
         label='Close')

# Customize and show the plot
plt.legend()
plt.title('EMAs')
plt.show()

EMA plot

SMA vs. EMA

EMA is more sensitive to the most recent price movement

A plot to show SMA vs EMA calculated with the same lookback window

Let's practice!

Financial Trading in Python