Hi Everyone,

Looks like I may have run into a bug for the contourf function. I was able to reproduce the problem on two OS X systems. One was based on 10.5 and the other was on 10.4. The problem appears when you use contourf with alpha < 1. With the transparency there appears to be streaks of lines pointing downward from the contour lines. Is this a bug that has been spotted before? Additional information is provided below with a python script to reproduce the problem.

Note, this bug was reproduced with a range of different parameters and input values. The script is the easiest way to reproduce the problem.

Cheers,

Eli

Mac OSX Darwin Kernel Version 9.5.0 (Leopard 10.5.5)

Matplotlib version: 0.98.3

Matplotlib was installed via EPD, version Py2.5 4.1.30101 i386

Code to show bug:

Most of the python code was borrowed from the Matplotlib examples

http://matplotlib.sourceforge.net/examples/pylab_examples/contour_demo.html?highlight=contours

###### Begin Python Code #######

import matplotlib

import numpy as np

import matplotlib.cm as cm

import matplotlib.mlab as mlab

import matplotlib.pyplot as plt

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)

Z = 10.0 * (Z2 - Z1)

plt.figure()

CS = plt.contourf(X, Y, Z,alpha = 0.7)

###### End Python Code #######