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Logarithmic Python outline contour color matplotlib

I have problems with a contour plot using logarithmic color scaling. I want to specify the levels manually. However, Matplotlib draws a color bar in a strange way - the labels do not fit well, and only one color appears. The idea is based on http://adversus.110mb.com/?cat=8

Is there anyone who can help me? I am using the latest version of git-repository matplotlib, v1.1.0 (2011-04-21)

import matplotlib.pyplot as plt import numpy as np from matplotlib.mlab import bivariate_normal from matplotlib.colors import LogNorm from matplotlib.backends.backend_pdf import PdfPages delta = 0.5 x = np.arange(-3.0, 4.001, delta) y = np.arange(-4.0, 3.001, delta) X, Y = np.meshgrid(x, y) Z = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0) fig = plt.figure() ax = fig.add_subplot(1,1,1) #axim = ax.imshow(Z, norm = LogNorm()) axim = ax.contourf(X,Y,Z,levels=[1e0,1e-1,1e-2,1e-3],cmap=plt.cm.jet,norm = LogNorm()) cb = fig.colorbar(axim) pp = PdfPages('fig.pdf') pp.savefig() pp.close() plt.show()

Many thanks for your help! It works fine, as you suggested ... However, I have another question: why matplotlib does not allow me to select the number of level lines in logarithmic mode:

 import matplotlib.pyplot as plt import numpy as np from matplotlib.mlab import bivariate_normal from matplotlib.colors import LogNorm from matplotlib.backends.backend_pdf import PdfPages delta = 0.5 x = np.arange(-3.0, 4.001, delta) y = np.arange(-4.0, 3.001, delta) X, Y = np.meshgrid(x, y) Z = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0) fig = plt.figure() ax = fig.add_subplot(1,1,1) #axim = ax.imshow(Z, norm = LogNorm()) #axim = ax.contourf(X,Y,Z,levels=[1e-3,1e-2,1e-1,1e0],cmap=plt.cm.jet,norm = LogNorm()) axim = ax.contourf(X,Y,Z,20,cmap=plt.cm.jet,norm = LogNorm()) cb = fig.colorbar(axim) pp = PdfPages('fig.pdf') pp.savefig() pp.close() plt.show()

http://i.stack.imgur.com/VeVFQ.png

That was my original problem ...

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python matplotlib logging plot contour
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2 answers

Therefore, it is easily fixed; your level order means the lowest level gets the last and therefore covers everything! Try:

 axim = ax.contourf(X,Y,Z,levels=[1e-3, 1e-2, 1e-1, 1e0],cmap=plt.cm.jet,norm = LogNorm())

and you should get the desired result.

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It seems levels expecting higher values. Try changing them to: levels=[1e-3, 1e-2, 1e-1, 1e0] and see if this problem resolves.

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