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Merged
merged 3 commits into from
Apr 30, 2012
Merged

Add norm parameter to streamplot. #849

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5e1a266
Add `norm` parameter to `streamplot`.
tonysyu Apr 22, 2012
0332aa4
Fix: forgot autodoc tag
tonysyu Apr 22, 2012
7d435d4
Remove note about return value of streamplot.
tonysyu Apr 28, 2012
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4 changes: 3 additions & 1 deletion lib/matplotlib/axes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6389,13 +6389,15 @@ def quiver(self, *args, **kw):
quiver.__doc__ = mquiver.Quiver.quiver_doc

def streamplot(self, x, y, u, v, density=1, linewidth=None, color=None,
cmap=None, arrowsize=1, arrowstyle='-|>', minlength=0.1):
cmap=None, norm=None, arrowsize=1, arrowstyle='-|>',
minlength=0.1):
if not self._hold: self.cla()
lines = mstream.streamplot(self, x, y, u, v,
density=density,
linewidth=linewidth,
color=color,
cmap=cmap,
norm=norm,
arrowsize=arrowsize,
arrowstyle=arrowstyle,
minlength=minlength)
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4 changes: 2 additions & 2 deletions lib/matplotlib/pyplot.py
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Expand Up @@ -2658,15 +2658,15 @@ def step(x, y, *args, **kwargs):
# This function was autogenerated by boilerplate.py. Do not edit as
# changes will be lost
@autogen_docstring(Axes.streamplot)
def streamplot(x, y, u, v, density=1, linewidth=None, color=None, cmap=None, arrowsize=1, arrowstyle='-|>', minlength=0.10000000000000001, hold=None):
def streamplot(x, y, u, v, density=1, linewidth=None, color=None, cmap=None, norm=None, arrowsize=1, arrowstyle='-|>', minlength=0.10000000000000001, hold=None):
ax = gca()
# allow callers to override the hold state by passing hold=True|False
washold = ax.ishold()

if hold is not None:
ax.hold(hold)
try:
ret = ax.streamplot(x, y, u, v, density, linewidth, color, cmap, arrowsize, arrowstyle, minlength)
ret = ax.streamplot(x, y, u, v, density, linewidth, color, cmap, norm, arrowsize, arrowstyle, minlength)
draw_if_interactive()
finally:
ax.hold(washold)
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33 changes: 19 additions & 14 deletions lib/matplotlib/streamplot.py
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Expand Up @@ -11,7 +11,8 @@


def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
cmap=None, arrowsize=1, arrowstyle='-|>', minlength=0.1):
cmap=None, norm=None, arrowsize=1, arrowstyle='-|>',
minlength=0.1):
"""Draws streamlines of a vector flow.

Parameters
Expand All @@ -31,19 +32,23 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
*color* : matplotlib color code, or 2d array
Streamline color. When given an array with the same shape as
velocities, *color* values are converted to colors using *cmap*.
*cmap* : Colormap
*cmap* : :class:`~matplotlib.colors.Colormap`
Colormap used to plot streamlines and arrows. Only necessary when using
an array input for *color*.
*norm* : :class:`~matplotlib.colors.Normalize`
Normalize object used to scale luminance data to 0, 1. If None, stretch
(min, max) to (0, 1). Only necessary when *color* is an array.
*arrowsize* : float
Factor scale arrow size.
*arrowstyle* : str
Arrow style specification. See `matplotlib.patches.FancyArrowPatch`.
Arrow style specification.
See :class:`~matplotlib.patches.FancyArrowPatch`.
*minlength* : float
Minimum length of streamline in axes coordinates.

Returns
-------
*streamlines* : `matplotlib.collections.LineCollection`
*streamlines* : :class:`~matplotlib.collections.LineCollection`
Line collection with all streamlines as a series of line segments.
Currently, there is no way to differentiate between line segments
on different streamlines (other than manually checking that segments
Expand All @@ -62,7 +67,8 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
line_kw = {}
arrow_kw = dict(arrowstyle=arrowstyle, mutation_scale=10*arrowsize)

if isinstance(color, np.ndarray):
use_multicolor_lines = isinstance(color, np.ndarray)
if use_multicolor_lines:
assert color.shape == grid.shape
line_colors = []
else:
Expand Down Expand Up @@ -95,12 +101,11 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
if t != None:
trajectories.append(t)

# Load up the defaults - needed to get the color right.
if isinstance(color, np.ndarray):
norm = matplotlib.colors.normalize(color.min(), color.max())
if cmap == None: cmap = matplotlib.cm.get_cmap(
matplotlib.rcParams['image.cmap'])

if use_multicolor_lines:
if norm is None:
norm = matplotlib.colors.normalize(color.min(), color.max())
if cmap is None:
cmap = matplotlib.cm.get_cmap(matplotlib.rcParams['image.cmap'])

streamlines = []
for t in trajectories:
Expand All @@ -113,7 +118,7 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
points = np.transpose([tx, ty]).reshape(-1, 1, 2)
streamlines.extend(np.hstack([points[:-1], points[1:]]))

## Add arrows half way along each trajectory.
# Add arrows half way along each trajectory.
s = np.cumsum(np.sqrt(np.diff(tx)**2 + np.diff(ty)**2))
n = np.searchsorted(s, s[-1] / 2.)
arrow_tail = (tx[n], ty[n])
Expand All @@ -124,7 +129,7 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
line_kw['linewidth'].extend(line_widths)
arrow_kw['linewidth'] = line_widths[n]

if isinstance(color, np.ndarray):
if use_multicolor_lines:
color_values = interpgrid(color, tgx, tgy)[:-1]
line_colors.extend(color_values)
arrow_kw['color'] = cmap(norm(color_values[n]))
Expand All @@ -133,7 +138,7 @@ def streamplot(axes, x, y, u, v, density=1, linewidth=None, color=None,
axes.add_patch(p)

lc = matplotlib.collections.LineCollection(streamlines, **line_kw)
if isinstance(color, np.ndarray):
if use_multicolor_lines:
lc.set_array(np.asarray(line_colors))
lc.set_cmap(cmap)
lc.set_norm(norm)
Expand Down