Matplotlib 3.0 Cookbook

How to do it...

The following code plots a sine wave and annotates a point on the graph in both data and display co-ordinates:

1. Define the figure and add an axis to it:

fig = plt.figure()ax = fig.add_subplot(111)

2. Define the data for the sine curve and plot it:

theta = np.linspace(0, 2*np.pi, 128)y = np.sin(theta)ax.plot(theta, y, 'r-*')

3. Define the point on the data co-ordinate system and transform it to the display co-ordinate system:

xdata, ydata = 3, 0xdisplay, ydisplay = ax.transData.transform_point((xdata, ydata))

4. Define the attributes of the bounding box to be used around the text description:

bbox = dict(boxstyle="round", fc="1.0")

5. Define the arrow properties to be used in the annotation:

arrowprops = dict(arrowstyle="->", ...