matplotlib - Label python data points on plot

Question

I searched for ages (hours which is like ages) to find the answer to a really annoying (seemingly basic) problem, and because I cant find a question that quite fits the answer I am posting a question and answering it in the hope that it will save someone else the huge amount of time I just spent on my noobie plotting skills.

If you want to label your plot points using python matplotlib

from matplotlib import pyplot as plt

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

A = anyarray
B = anyotherarray

plt.plot(A,B)
for i,j in zip(A,B):
    ax.annotate('%s)' %j, xy=(i,j), xytext=(30,0), textcoords='offset points')
    ax.annotate('(%s,' %i, xy=(i,j))

plt.grid()
plt.show()

I know that xytext=(30,0) goes along with the textcoords, you use those 30,0 values to position the data label point, so its on the 0 y axis and 30 over on the x axis on its own little area.

You need both the lines plotting i and j otherwise you only plot x or y data label.

You get something like this out (note the labels only):

Its not ideal, there is still some overlap - but its better than nothing which is what I had..

Answer 1

How about print (x, y) at once.

from matplotlib import pyplot as plt

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

A = -0.75, -0.25, 0, 0.25, 0.5, 0.75, 1.0
B = 0.73, 0.97, 1.0, 0.97, 0.88, 0.73, 0.54

ax.plot(A,B)
for xy in zip(A, B):                                       # <--
    ax.annotate('(%s, %s)' % xy, xy=xy, textcoords='data') # <--

ax.grid()
plt.show()