Hello again,
I finally found the command I was looking for. It is the to_polygons().
Here is what worked :
# make a LineCollection of contours
col=contour(X,Y,Z,LevelsNumber).collections
for i in np.arange(0,LevelsNumber,1):
polygoni=col[i].get_paths()[0].to_polygons()[0]
print polygoni
All the vertices in each collections are extracted to the "polygoni".
Thanks again to Jeff and Patrick !
By the way, I found out that I do not actually need this procedure to
achieve may goal
which was to make a contour plot in ternary coordinates.
Eli
On Tue, Jan 27, 2009 at 11:08 PM, Patrick Marsh <patrickmars...@gmail.com>wrote:
> On Tue, Jan 27, 2009 at 7:16 PM, Eli Brosh <ebro...@gmail.com> wrote:
> > Many thanks to Jeff and to Patric !
> > I will try to work along the line suggested by Jeff.
> > Patric, please send me your code.
> > I hope to learn from it.
> >
> > Thanks again,
> > Eli
>
>
> Here is a template that can be used. I use this for meteorological
> models, but should work with any gridded file.
>
>
> import numpy as np
> from mpl_toolkits.basemap import Basemap
>
> f = (some gridded file)
> X = np.array(grab longitudes from f)
> Y = np.array(grab latitudes from f)
> field = np.array(grab field to be contoured from f)
> map = Basemap(make a Basemap call here)
> level = np.arange(minval, maxval, interval)
> col = map.contour(X, Y, field, level).collections
>
> for vertex in col[i].get_paths(): # GET THE PATHS FOR THE EACH
> CONTOUR BY LOOPING THROUGH CONTOURS
> for vertex in xy.vertices: # ITERATE OVER THE PATH OBJECTS
> x, y = map(vertex[0],vertex[1],inverse=True) # vertex[0]
> and now 'x' is the longitude of the vertex and vertex[1] and now 'y'
> is the latitude of the vertex
>
>
> Let me know how this works.
>
> -Patrick
>
>
>
>
>
>
>
>
>
> >
> > On Tue, Jan 27, 2009 at 7:09 PM, Patrick Marsh <patrickmars...@gmail.com
> >
> > wrote:
> >>
> >> On Tue, Jan 27, 2009 at 5:33 PM, Jeff Whitaker <jsw...@fastmail.fm>
> wrote:
> >> > Eli Brosh wrote:
> >> >> Hello,
> >> >> I am trying to extract the coordinates of contour lines.
> >> >> I tried the following:
> >> >>
> >> >> cs = *contour*(Z)
> >> >> for lev, col in zip(cs.levels, cs.collections):
> >> >> s = col._segments
> >> >>
> >> >> that I found in a previous post (title "contouring", by Jose
> >> >> Gómez-Dans-2 <http://www.nabble.com/user/UserProfile.jtp?user=30071>
> >> >> Nov 30, 2007; 07:47am ) .
> >> >>
> >> >> I hoped that s will be a list of numpy arrays, each containing the
> >> >> (x,y) vertices
> >> >> defining a contour line at level lev.
> >> >> However, I got an error message:
> >> >> AttributeError: 'LineCollection' object has no attribute '_segments'
> >> >>
> >> >>
> >> >> How is it possible to get coordinates of the contours, similar to the
> >> >> MATLAB command
> >> >> [C,H] = *CONTOUR*(...)
> >> >> where the result in C is the coordinates of the contours.
> >> >>
> >> >> A similar question appeared in a post "contour data" (by Albert Swart
> >> >> <http://www.nabble.com/user/UserProfile.jtp?user=382945> May 17,
> 2006;
> >> >> 09:42am) but I could not understand the answer.
> >> >> Is it possible to get more specific directions with a simple example
> ?
> >> >>
> >> >>
> >> >> Thanks
> >> >> Eli
> >> > Eli: Calling get_paths() on each line collection in CS.collections
> will
> >> > return a list of Path objects. From the Path objects, you can get a
> Nx2
> >> > array of vertices from the "vertices" attribute. There are no
> examples
> >> > that I know of, but if you get it to do what you want to do, it would
> be
> >> > great if you could contribute an example. As you noted, this question
> >> > has come up several times before.
> >> >
> >> > -Jeff
> >> >
> >> > --
> >> > Jeffrey S. Whitaker Phone : (303)497-6313
> >> > Meteorologist FAX : (303)497-6449
> >> > NOAA/OAR/PSD R/PSD1 Email : jeffrey.s.whita...@noaa.gov
> >> > 325 Broadway Office : Skaggs Research Cntr 1D-113
> >> > Boulder, CO, USA 80303-3328 Web : http://tinyurl.com/5telg
> >> >
> >> >
> >> >
> >> >
> >> >
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> >> >
> >>
> >> I'm not sure if this is entirely what you (Eli) are looking for, but I
> >> have code that will contour model data on a map and then extract the
> >> lat,lon pairs of all the vertices. If this is what you are looking
> >> for, I'm happy to share what I've done.
> >>
> >> -Patrick
> >>
> >> --
> >> Patrick Marsh
> >> Graduate Research Assistant
> >> School of Meteorology
> >> University of Oklahoma
> >> http://www.patricktmarsh.com
> >
> >
>
>
>
> --
> Patrick Marsh
> Graduate Research Assistant
> School of Meteorology
> University of Oklahoma
> http://www.patricktmarsh.com
>
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