How to add hovering annotations in matplotlib
It seems none of the other answers here actually answer the question. So here is a code that uses a scatter and shows an annotation upon hovering over the scatter points.
import matplotlib.pyplot as pltimport numpy as np; np.random.seed(1)x = np.random.rand(15)y = np.random.rand(15)names = np.array(list("ABCDEFGHIJKLMNO"))c = np.random.randint(1,5,size=15)norm = plt.Normalize(1,4)cmap = plt.cm.RdYlGnfig,ax = plt.subplots()sc = plt.scatter(x,y,c=c, s=100, cmap=cmap, norm=norm)annot = ax.annotate("", xy=(0,0), xytext=(20,20),textcoords="offset points", bbox=dict(boxstyle="round", fc="w"), arrowprops=dict(arrowstyle="->"))annot.set_visible(False)def update_annot(ind): pos = sc.get_offsets()[ind["ind"][0]] annot.xy = pos text = "{}, {}".format(" ".join(list(map(str,ind["ind"]))), " ".join([names[n] for n in ind["ind"]])) annot.set_text(text) annot.get_bbox_patch().set_facecolor(cmap(norm(c[ind["ind"][0]]))) annot.get_bbox_patch().set_alpha(0.4)def hover(event): vis = annot.get_visible() if event.inaxes == ax: cont, ind = sc.contains(event) if cont: update_annot(ind) annot.set_visible(True) fig.canvas.draw_idle() else: if vis: annot.set_visible(False) fig.canvas.draw_idle()fig.canvas.mpl_connect("motion_notify_event", hover)plt.show()
Because people also want to use this solution for a line plot instead of a scatter, the following would be the same solution for plot (which works slightly differently).
In case someone is looking for a solution for lines in twin axes, refer to How to make labels appear when hovering over a point in multiple axis?
In case someone is looking for a solution for bar plots, please refer to e.g. this answer.
This solution works when hovering a line without the need to click it:
import matplotlib.pyplot as plt# Need to create as global variable so our callback(on_plot_hover) can accessfig = plt.figure()plot = fig.add_subplot(111)# create some curvesfor i in range(4): # Giving unique ids to each data member plot.plot( [i*1,i*2,i*3,i*4], gid=i)def on_plot_hover(event): # Iterating over each data member plotted for curve in plot.get_lines(): # Searching which data member corresponds to current mouse position if curve.contains(event)[0]: print "over %s" % curve.get_gid()fig.canvas.mpl_connect('motion_notify_event', on_plot_hover) plt.show()
From http://matplotlib.sourceforge.net/examples/event_handling/pick_event_demo.html :
from matplotlib.pyplot import figure, showimport numpy as npyfrom numpy.random import randif 1: # picking on a scatter plot (matplotlib.collections.RegularPolyCollection) x, y, c, s = rand(4, 100) def onpick3(event): ind = event.ind print('onpick3 scatter:', ind, npy.take(x, ind), npy.take(y, ind)) fig = figure() ax1 = fig.add_subplot(111) col = ax1.scatter(x, y, 100*s, c, picker=True) #fig.savefig('pscoll.eps') fig.canvas.mpl_connect('pick_event', onpick3)show()- This recipe draws an annotation on picking a data point: http://scipy-cookbook.readthedocs.io/items/Matplotlib_Interactive_Plotting.html .
- This recipe draws a tooltip, but it requires wxPython:Point and line tooltips in matplotlib?