From: Angus McMorland <amcmorl@gm...>  20110328 01:25:37

On 27 March 2011 20:47, Warren Weckesser <warren.weckesser@...> wrote: > I'm using matplotlib 1.0.1. I have the following simple script to plot a > surface: > >  > from numpy import linspace, sin, cos, meshgrid > > from matplotlib.pyplot import figure, show, xlabel, ylabel > from matplotlib import cm > from mpl_toolkits.mplot3d import Axes3D > > n = 35 > x = linspace(5, 5, n) > y = linspace(0, 10, n) > X, Y = meshgrid(x, y) > Z = X*sin(X)*cos(0.25*Y) > > fig = figure() > ax = fig.gca(projection='3d') > ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=cm.copper) > xlabel('x') > ylabel('y') > show() >  > > It works finemany thanks to all the folks working on the 3D plots! > > But notice that Axes3D is imported from matplotlib.mplot3d, but never > explicitly used. If I comment out that import, however, I get the following > traceback: >  > Traceback (most recent call last): > File "surf_demo.py", line 15, in <module> > ax = fig.gca(projection='3d') > File > "/Library/Frameworks/Python.framework/Versions/7.0/lib/python2.7/sitepackages/matplotlib/figure.py", > line 965, in gca > return self.add_subplot(111, **kwargs) > File > "/Library/Frameworks/Python.framework/Versions/7.0/lib/python2.7/sitepackages/matplotlib/figure.py", > line 675, in add_subplot > projection_class = get_projection_class(projection) > File > "/Library/Frameworks/Python.framework/Versions/7.0/lib/python2.7/sitepackages/matplotlib/projections/__init__.py", > line 61, in get_projection_class > raise ValueError("Unknown projection '%s'" % projection) > ValueError: Unknown projection '3d' >  > > Is this expected? Yes, the last lines of axes3d.py, which get called when Axes3D is imported, are: import matplotlib.projections as proj proj.projection_registry.register(Axes3D) which is what lets matplotlib know about the '3d' projection. Just importing the Axes3D module therefore performs the necessary registration of the projection to be able to use it in subsequent code. Code analysis tools like rope don't know about this behind the scenes stuff though, so it looks like a redundant import to them. Angus.  AJC McMorland Postdoctoral research fellow Neurobiology, University of Pittsburgh 