Appendix O — Candlestick Charts with plotly

In financial applications, we often have access to OHLC data (containing the open, high, low, and close price on each day). We can use a candlestick chart can help us see the movement of the price within each day.

To implement a candlestick chart, we can use the Candlestick class from plotly’s Graph Objects sub-library.

We start with some OHLC data:

ohlc_data = [
    {"date": "2030-03-16", "open": 236.2800, "high": 240.0550, "low": 235.9400, "close": 237.7100, "volume": 28092196},
    {"date": "2030-03-15", "open": 234.9600, "high": 235.1850, "low": 231.8100, "close": 234.8100, "volume": 26042669},
    {"date": "2030-03-12", "open": 234.0100, "high": 235.8200, "low": 233.2300, "close": 235.7500, "volume": 22653662},
    {"date": "2030-03-11", "open": 234.9600, "high": 239.1700, "low": 234.3100, "close": 237.1300, "volume": 29907586},
    {"date": "2030-03-10", "open": 237.0000, "high": 237.0000, "low": 232.0400, "close": 232.4200, "volume": 29746812}
]

Mapping the data to get into a format the chart likes (separate lists):

dates = []
opens = []
highs = []
lows = []
closes = []

for item in ohlc_data:
    dates.append(item["date"])
    opens.append(item["open"])
    highs.append(item["high"])
    lows.append(item["low"])
    closes.append(item["close"])

Finally, creating the chart:

from plotly.graph_objects import Figure, Candlestick

stick = Candlestick(x=dates, open=opens, high=highs, low=lows, close=closes)

fig = Figure(data=[stick])
fig.update_layout(title="Example Candlestick Chart")
fig.show()