[Python] Drawing Candlestick Charts with mplfinance

This post outlines the steps to download Google's stock price data and create a candlestick chart using Python, matplotlib, and the yahooquery library. We will illustrate how to plot the basic candlestick chart, add 5-day and 20-day moving averages, and utilize built-in styles provided by mplfinance. If you're unfamiliar with how to use the yahooquery library, please refer to the previous post [Python] Yahooquery: Retrieving and Managing Past Stock and Financial Data.

# Obtaining Google's Stock Price Data

The code snippet to fetch Google's stock price data for the last 60 days is as follows:

from yahooquery import Ticker

google = Ticker('GOOGL')
price_data = google.history(period='60d')

# Preparing the Data

Next, manipulate the data as follows:

import pandas as pd

price_data.reset_index(inplace=True)
price_data['date'] = pd.to_datetime(price_data['date'])
price_data.set_index('date', inplace=True)

# Plotting the Candlestick Chart

# Basic Candlestick Chart

import mplfinance as mpf

mc = mpf.make_marketcolors(up='g',down='r')
s  = mpf.make_mpf_style(marketcolors=mc)

mpf.plot(price_data,
         style=s,
         type='candle',
         volume=True,
         tight_layout=True)

Here's the resulting image:

This chart shows the basic candlestick chart without moving averages.

# Adding 5-day and 20-day Moving Averages

mpf.plot(price_data,
         style=s,
         type='candle',
         mav=(5, 20),
         volume=True,
         tight_layout=True)

Here's the image:

This chart includes the 5-day and 20-day moving averages, enhancing the trend analysis.

# Utilizing Built-in mplfinance Styles

mplfinance comes with several built-in styles that you can use without creating a custom style. Instead of defining market colors as we did with:

mc = mpf.make_marketcolors(up='g',down='r')
s  = mpf.make_mpf_style(marketcolors=mc)

You can use one of the following built-in styles:

['binance', 'blueskies', 'brasil', 'charles', 'checkers', 'classic', 'default', 'ibd', 'kenan', 'mike', 'nightclouds', 'sas', 'starsandstripes', 'yahoo']

For example, to use the Yahoo Finance-like style:

mpf.plot(price_data,
         style='yahoo',
         type='candle',
         mav=(5, 20),
         volume=True,
         tight_layout=True)

Here's the resulting image with Yahoo Finance-like style:

This approach simplifies the customization process by utilizing predefined styles that suit different preferences.

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This post has demonstrated how to visualize Google's stock price data using a candlestick chart. By employing the mplfinance library, it's possible to create detailed visualizations, adding features like moving averages and utilizing the library's built-in styles. This method can serve as a powerful tool for financial analysis and market trend observation.

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# FAQs

1. What is the yahooquery library, and how do I use it? Refer to the previous post [Python] Yahooquery: Retrieving and Managing Past Stock and Financial Data.

2. Can I plot the candlestick chart for a different stock? Replace 'GOOGL' with the desired stock symbol.

3. How can I customize the colors of the candlestick chart? Modify the parameters in the make_marketcolors function.

4. Can I change the time period for which the data is fetched? Replace 60d with the desired time period.

5. What is a candlestick chart, and why is it used? A candlestick chart is a graphical representation of price movements, widely used in financial analysis.