BUG: manual clabel positioning broke between 1.2 and 1.3 #2475
Description
The bug is reported to the matplotlib-users list by Felix Patzelt on Sept. 28:
http://matplotlib.1069221.n5.nabble.com/Broken-clabel-manual-True-in-1-3-0-td42124.html.
Below is a slightly edited version of the script he provided to make it easy to reproduce the problem. I have verified that the error occurs in master.
import numpy as np
from matplotlib import mlab
import pylab as plt
# Broken manual labelling demo
# Adapted from pylab_examples example code: contour_demo.py
delta = 0.025
x = np.arange(-3.0, 3.0, delta)
y = np.arange(-2.0, 2.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
# difference of Gaussians
Z = 10.0 * (Z2 - Z1)
plt.figure()
CS = plt.contour(X, Y, Z)
plt.clabel(CS, inline=1, fontsize=10, manual=True)
plt.title('Position labels manually')
plt.show()