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SF.net SVN: matplotlib:[7836] trunk/matplotlib/lib/matplotlib/quiver.py
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From: <ef...@us...> - 2009-10-01 02:28:23
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Revision: 7836
http://matplotlib.svn.sourceforge.net/matplotlib/?rev=7836&view=rev
Author: efiring
Date: 2009-10-01 02:28:14 +0000 (Thu, 01 Oct 2009)
Log Message:
-----------
Add scale_units kwarg, additional 'xy' units option.
Modified Paths:
--------------
trunk/matplotlib/lib/matplotlib/quiver.py
Modified: trunk/matplotlib/lib/matplotlib/quiver.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/quiver.py 2009-09-30 13:28:37 UTC (rev 7835)
+++ trunk/matplotlib/lib/matplotlib/quiver.py 2009-10-01 02:28:14 UTC (rev 7836)
@@ -72,7 +72,7 @@
* 'dots' or 'inches': pixels or inches, based on the figure dpi
- * 'x' or 'y': *X* or *Y* data units
+ * 'x', 'y', or 'xy': *X*, *Y*, or sqrt(X^2+Y^2) data units
The arrows scale differently depending on the units. For
'x' or 'y', the arrows get larger as one zooms in; for other
@@ -81,6 +81,7 @@
height of the axes, respectively, when the the window is resized;
for 'dots' or 'inches', resizing does not change the arrows.
+
*angles*: ['uv' | 'xy' | array]
With the default 'uv', the arrow aspect ratio is 1, so that
if *U*==*V* the angle of the arrow on the plot is 45 degrees
@@ -90,11 +91,21 @@
of values in degrees, CCW from the *x*-axis.
*scale*: [ None | float ]
- data units per arrow unit, e.g. m/s per plot width; a smaller
+ data units per arrow length unit, e.g. m/s per plot width; a smaller
scale parameter makes the arrow longer. If *None*, a simple
autoscaling algorithm is used, based on the average vector length
- and the number of vectors.
+ and the number of vectors. The arrow length unit is given by
+ the *scale_units* parameter
+ *scale_units*: None, or any of the *units* options. For example,
+ if *scale_units* is 'inches', *scale* is 2.0, and (u,v) = (1,0),
+ then the vector will be 0.5 inches long. If *scale_units* is
+ 'width', then the vector will be half the width of the axes.
+ If *scale_units* is 'x' then the vector will be 0.5 x-axis
+ units. To plot vectors in the x-y plane, with u and v having
+ the same units as x and y, use
+ "angles='xy', scale_units='xy', scale=1".
+
*width*:
shaft width in arrow units; default depends on choice of units,
above, and number of vectors; a typical starting value is about
@@ -390,6 +401,7 @@
self.minshaft = kw.pop('minshaft', 1)
self.minlength = kw.pop('minlength', 1)
self.units = kw.pop('units', 'width')
+ self.scale_units = kw.pop('scale_units', None)
self.angles = kw.pop('angles', 'uv')
self.width = kw.pop('width', None)
self.color = kw.pop('color', 'k')
@@ -418,7 +430,8 @@
def _init(self):
- """initialization delayed until first draw;
+ """
+ Initialization delayed until first draw;
allow time for axes setup.
"""
# It seems that there are not enough event notifications
@@ -429,14 +442,15 @@
sx, sy = trans.inverted().transform_point(
(ax.bbox.width, ax.bbox.height))
self.span = sx
- sn = max(8, min(25, math.sqrt(self.N)))
if self.width is None:
+ sn = max(8, min(25, math.sqrt(self.N)))
self.width = 0.06 * self.span / sn
@allow_rasterization
def draw(self, renderer):
self._init()
- if self._new_UV or self.angles == 'xy':
+ if (self._new_UV or self.angles == 'xy'
+ or self.scale_units in ['x','y', 'xy']):
verts = self._make_verts(self.U, self.V)
self.set_verts(verts, closed=False)
self._new_UV = False
@@ -460,27 +474,46 @@
self.set_array(C)
self._new_UV = True
- def _set_transform(self):
+ def _dots_per_unit(self, units):
+ """
+ Return a scale factor for converting from units to pixels
+ """
ax = self.ax
- if self.units in ('x', 'y'):
- if self.units == 'x':
+ if units in ('x', 'y', 'xy'):
+ if units == 'x':
dx0 = ax.viewLim.width
dx1 = ax.bbox.width
- else:
+ elif units == 'y':
dx0 = ax.viewLim.height
dx1 = ax.bbox.height
+ else: # 'xy' is assumed
+ dxx0 = ax.viewLim.width
+ dxx1 = ax.bbox.width
+ dyy0 = ax.viewLim.height
+ dyy1 = ax.bbox.height
+ dx1 = np.sqrt(dxx1*dxx1+dyy1*dyy1)
+ dx0 = np.sqrt(dxx0*dxx0+dyy0*dyy0)
dx = dx1/dx0
else:
- if self.units == 'width':
+ if units == 'width':
dx = ax.bbox.width
- elif self.units == 'height':
+ elif units == 'height':
dx = ax.bbox.height
- elif self.units == 'dots':
+ elif units == 'dots':
dx = 1.0
- elif self.units == 'inches':
+ elif units == 'inches':
dx = ax.figure.dpi
else:
raise ValueError('unrecognized units')
+ return dx
+
+ def _set_transform(self):
+ """
+ Sets the PolygonCollection transform to go
+ from arrow width units to pixels.
+ """
+ dx = self._dots_per_unit(self.units)
+ self._trans_scale = dx # pixels per arrow width unit
trans = transforms.Affine2D().scale(dx)
self.set_transform(trans)
return trans
@@ -503,8 +536,18 @@
else:
amean = a.mean()
scale = 1.8 * amean * sn / self.span # crude auto-scaling
- self.scale = scale
- length = a/(self.scale*self.width)
+ # scale is typical arrow length as a multiple
+ # of the arrow width
+ if self.scale_units is None:
+ if self.scale is None:
+ self.scale = scale
+ widthu_per_lenu = 1.0
+ else:
+ dx = self._dots_per_unit(self.scale_units)
+ widthu_per_lenu = dx/self._trans_scale
+ if self.scale is None:
+ self.scale = scale * widthu_per_lenu
+ length = a * (widthu_per_lenu / (self.scale * self.width))
X, Y = self._h_arrows(length)
if self.angles == 'xy':
theta = self._angles(U, V)
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