In a matplotlib plot, can I highlight specific x-value ranges?

Question

I'm making a visualization of historical stock data for a project, and I'd like to highlight regions of drops. For instance, when the stock is experiencing significant drawdown, I would like to highlight it with a red region.

Can I do this automatically, or will I have to draw a rectangle or something?

Answer 1

Have a look at axvspan (and axhspan for highlighting a region of the y-axis).

import matplotlib.pyplot as plt  plt.plot(range(10)) plt.axvspan(3, 6, color='red', alpha=0.5) plt.show() 

If you're using dates, then you'll need to convert your min and max x values to matplotlib dates. Use matplotlib.dates.date2num for datetime objects or matplotlib.dates.datestr2num for various string timestamps.

import matplotlib.pyplot as plt import matplotlib.dates as mdates import datetime as dt  t = mdates.drange(dt.datetime(2011, 10, 15), dt.datetime(2011, 11, 27),                   dt.timedelta(hours=2)) y = np.sin(t)  fig, ax = plt.subplots() ax.plot_date(t, y, 'b-') ax.axvspan(*mdates.datestr2num(['10/27/2011', '11/2/2011']), color='red', alpha=0.5) fig.autofmt_xdate() plt.show()