As we just saw, adding annotations is relatively simple: we can use plt.annotate(), and pass in parameters for text and (xy) position. To recap:
plt.annotate() also takes many more parameters for more detailed annotations, including:
fontsizeandcolorhaandvato set horizontal and vertical alignmentbackgroundcolor
We can also use plt.annotate() to add arrows to a graph, with the following parameters:
arrowpropsto style an arrow from the annotation to a pointxytextto reposition the text, if an arrow is used – the arrowhead will automatically be positioned at(xy)
Heads up: arrowprops is a dictionary of parameters – so we’ll actually end up with a list of arrowprops parameters nested inside our list of plt.annotate parameters.
In this exercise, we’ll further improve our species count graph by using annotations to highlight a few tree genuses of interest.
Instructions
Now, let’s add annotations to highlight the Banara genus, which occupies a dramatically different position in each type of forest. We’ll do the annotation here, and add an arrow in the next step. Make an annotation of 'Banara' on each graph, with font size of 14 and the color 'royalblue' to match the Banara bar color. Set the xy value for Primary Forest to (77, 3). Set xy value for Secondary Forest to (3.5, 48). Set the xy value for Selectively Logged Forest to (33, 5).
Let’s add arrows to these labels. Within the arrowprops dict, set the arrowstyle to '-|>' for a solid-line arrow. Set the color to royalblue to match the annotation. Once we add an arrow property, the arrowhead will automatically be placed at the xy position we just set. To re-set the text at the proper position, we set it an xytext value. Set the xytext value for Primary Forest to (75, 20). Set xytext value for Secondary Forest to (8, 60). Set the xytext value for Selectively Logged Forest to (31, 20).