On 4/3/12 2:55 PM, Antonio Russo wrote:
Hello. I would like to be able to do an implicit_plot, but only inside a
particular region (much like is allowed with implicit_plot3d, with its region
option). I seem to be having trouble using Sage's revision control system
(which is why this patch is not in the standard form), but that is another
issue.
I have attached the patch, which is really very simple. Let me know if there is
anything else I can do to help get this functionality added (like maybe send
this as an attachment, which I do not see an obvious way to do).
This looks great. The typical thing to do is:
1. Create a trac account: http://trac.sagemath.org/sage_trac/
2. Create a ticket on trac and upload the patch (attach the patch to the
trac)
Please CC me on the ticket (username is jason).
Thanks,
Jason
diff --git a/sage/plot/contour_plot.py b/sage/plot/contour_plot.py
--- a/sage/plot/contour_plot.py
+++ b/sage/plot/contour_plot.py
@@ -203,7 +203,7 @@
@suboptions('colorbar', orientation='vertical', format=None, spacing=None)
@suboptions('label', fontsize=9, colors='blue', inline=None, inline_spacing=3,
fmt="%1.2f")
-@options(plot_points=100, fill=True, contours=None, linewidths=None,
linestyles=None, labels=False, frame=True, axes=False, colorbar=False,
legend_label=None)
+@options(plot_points=100, fill=True, contours=None, linewidths=None,
linestyles=None, labels=False, frame=True, axes=False, colorbar=False,
legend_label=None, region=None)
def contour_plot(f, xrange, yrange, **options):
r"""
``contour_plot`` takes a function of two variables, `f(x,y)`
@@ -299,6 +299,11 @@
- ``legend_label`` -- the label for this item in the legend
+ - ``region`` - (default: None) If region is given, it must be a Python
+ callable. Only segments of the surface where region(x,y) returns a
+ number>0 will be included in the plot. (Note that returning a Python
+ boolean is acceptable, since True == 1 and False == 0).
+
EXAMPLES:
Here we plot a simple function of two variables. Note that
@@ -467,13 +472,29 @@
"""
from sage.plot.plot import Graphics
from sage.plot.misc import setup_for_eval_on_grid
- g, ranges = setup_for_eval_on_grid([f], [xrange, yrange],
options['plot_points'])
- g = g[0]
+
+ region = options.pop('region')
+ ev = [f] if region is None else [f,region]
+
+ F, ranges = setup_for_eval_on_grid(ev, [xrange, yrange],
options['plot_points'])
+ g = F[0]
xrange,yrange=[r[:2] for r in ranges]
xy_data_array = [[g(x, y) for x in xsrange(*ranges[0],
include_endpoint=True)]
for y in xsrange(*ranges[1],
include_endpoint=True)]
+ if region is not None:
+ import numpy
+
+ xy_data_array = numpy.ma.asarray(xy_data_array,dtype=float)
+
+ m = F[1]
+
+ mask = numpy.asarray([[m(x, y)<=0 for x in xsrange(*ranges[0],
include_endpoint=True)]
+ for y in xsrange(*ranges[1],
include_endpoint=True)],dtype=bool)
+
+ xy_data_array[mask] = numpy.ma.masked
+
g = Graphics()
g._set_extra_kwds(Graphics._extract_kwds_for_show(options,
ignore=['xmin', 'xmax']))
g.add_primitive(ContourPlot(xy_data_array, xrange, yrange, options))
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