On Thu, May 21, 2009 at 9:31 PM, Ondrej Certik <[email protected]> wrote:
> Hi,
>
> I have a set of vertices in 2D as triples (x, y, val), where the x, y
> are 2D coordinates and "val" is the scalar value of the finite element
> solution, here is an example:
>
> In [54]: l.get_vertices()
> Out[54]:
> array([[ 0.00000000e+00, -1.00000000e+00, -2.22396971e-17],
> [ 1.00000000e+00, -1.00000000e+00, -1.64798730e-17],
> [ -1.00000000e+00, 0.00000000e+00, 8.09899023e-17],
> ...,
> [ 1.48437500e-01, -1.56250000e-02, 1.62359362e-01],
> [ 1.32812500e-01, 0.00000000e+00, 1.56012622e-01],
> [ 1.32812500e-01, -1.56250000e-02, 1.50562411e-01]])
>
>
> and I also have a set of triangles that connect those points, here is
> an example:
>
> In [55]: l.get_triangles()
> Out[55]:
> array([[ 3, 5448, 29],
> [ 27, 5445, 28],
> [ 29, 28, 26],
> ...,
> [5499, 5498, 5479],
> [5510, 5493, 5491],
> [5513, 5508, 5491]], dtype=int32)
>
>
> The triangles define the 2D domain. What is the best way to get this
> plotted with mpl? Should I write a loop using the "plot" command, or
> is there a better alternative? So far, I am using the contour command
> and I feed it just with the vertices, here is the code:
The best way is to define your triangles as an n length list of
triangle vertices
verts = [ ( (x00, y00), (x01, y01), (x02, y02)),
(x10, y10), (x11, y11), (x12, y12)),
...
]
and have an equal length array of intensities for color mapping.
vals = np.array(N_color_intensities)
Then create a PolyCollection:
import matplotlib.cm as cm
import matplotlib.collections as collections
col = collections.PolyCollection(verts)
col.set_array(val)
col.set_cmap(cm.hot)
ax.add_collection(col)
add_collection doesn't get the autoscaling limits, if I recall
correctly, so you will probably want to do
ax.set_xlim(xmin, xmax)
ax.set_ylim(ymin,. ymax)
See also:
http://matplotlib.sourceforge.net/api/collections_api.html#matplotlib.collections.PolyCollection
http://matplotlib.sourceforge.net/search.html?q=codex+PolyCollection
Unfortunately, we do not currently have support for interpolating
between adjacent polys in a PolyCollection, so the result may not look
as nice as mayavis.
JDH
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