Re: [Matplotlib-users] Contour line data

[Mike H. <mh...@us...>]

>>I don't think this is going to make it easy to do what you want

It might if I could find the x,y data in the LineCollection objects. There 
is an undocumented function in the LineCollection class called 
get_paths(), which looks like it returns a list of Path objects.  These 
path objects have a vertices property which looks like the stuff I want. 
I'll explore this for a while.  Anyone who knows more about these objects, 
feel free to chime in!

Thanks,

Mike



Eric Firing <ef...@ha...> 
12/03/08 01:59 PM

To
Mike Hearne <mh...@us...>
cc
mat...@li...
Subject
Re: [Matplotlib-users] Contour line data






Mike Hearne wrote:
> 
> How can I get the actual x,y data that represents the contour lines that 

> are drawn with the contour() function?
> 
> I'd like to be able to redraw portions of those lines with different 
> styles (dashed, dotted, etc.)
> 
> For example, given the following sample code (lifted from the 
> sourceforge example):
> 
> from pylab import *
> from numpy import *
> 
> delta = 0.025
> x = arange(-3.0, 3.0, delta)
> y = arange(-2.0, 2.0, delta)
> X, Y = meshgrid(x, y)
> Z1 = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
> Z2 = bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
> # difference of Gaussians
> Z = 10.0 * (Z2 - Z1)
> figure()
> cs = plt.contour(X, Y, Z)
> show()
> 
> How could I, for example, re-draw the lines in the region X [0 1] Y 
> [-1.5 -0.5] as dashed?
> 
> I could do it, I think, if I had the for all the lines in the plot.

I don't think this is going to make it easy to do what you want, but 
cs.collections is a list of LineCollection objects corresponding to the 
contour levels in cs.levels.

Eric