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polar plots do not properly handle units #4905

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polar plots do not properly handle units #4905

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9338d36
JRE - PolarAxes was not properly handling unitzed data. This fixes it.
Aug 11, 2015
676308a
Fixed accidental transpose of axes when dealing with units.
Aug 17, 2015
6e383f5
same as last commit, git just didn't get everything.
Aug 17, 2015
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34 changes: 29 additions & 5 deletions lib/matplotlib/projections/polar.py
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Original file line number Diff line number Diff line change
Expand Up @@ -399,6 +399,8 @@ def set_theta_offset(self, offset):
"""
Set the offset for the location of 0 in radians.
"""
# Make sure to strip away units
offset = self.convert_xunits(offset)
self._theta_offset = offset

def get_theta_offset(self):
Expand Down Expand Up @@ -521,9 +523,17 @@ def set_thetagrids(self, angles, labels=None, frac=None, fmt=None,
ACCEPTS: sequence of floats
"""
# Make sure we take into account unitized data
angles = self.convert_yunits(angles)
angles = np.asarray(angles, np.float_)
self.set_xticks(angles * (np.pi / 180.0))
if isinstance( angles[0], float ):
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Why do we need this if-branch? Is convert_yunits() not returning radians? If not, is that a regression?

# If the data is floats it is assumed to be degrees (as per the
# docsting for this method)
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docstring

angles = np.asarray(angles, np.float_)
self.set_xticks(angles * (np.pi / 180.0))
else:
# The unit converters are defined to return radians
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Silly question, where is this documented/implemented?

angles = self.convert_xunits(angles)
angles = np.asarray(angles, np.float_)
self.set_xticks(angles)

if labels is not None:
self.set_xticklabels(labels)
elif fmt is not None:
Expand Down Expand Up @@ -560,12 +570,16 @@ def set_rgrids(self, radii, labels=None, angle=None, fmt=None,
ACCEPTS: sequence of floats
"""
# Make sure we take into account unitized data
radii = self.convert_xunits(radii)
radii = self.convert_yunits(radii)
radii = np.asarray(radii)
rmin = radii.min()
if rmin <= 0:
raise ValueError('radial grids must be strictly positive')

# Handle unitized data
if angle is not None:
angle = self.convert_xunits(angle)

self.set_yticks(radii)
if labels is not None:
self.set_yticklabels(labels)
Expand All @@ -591,11 +605,21 @@ def format_coord(self, theta, r):
Return a format string formatting the coordinate using Unicode
characters.
"""
# Strip away any units
r = self.convert_yunits(r)
if not isinstance( theta, float ):
theta = self.convert_xunits(theta)
# Stripping away units makes theta be in radians.
# convert to degrees
theta = theta * (180.0 / np.pi)
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Maybe I am wrong, but this seems incorrect? The subsequent code already divides theta by pi and later multiplies by 180. In fact, the formatting string says that it is displaying radians first, then degrees second.

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I think you're right. Even though this function calls the arguments theta/r, it's called by matplotlib, so it's (sorta) x/y, meaning "theta" is in radians.


theta /= math.pi
# \u03b8: lower-case theta
# \u03c0: lower-case pi
# \u00b0: degree symbol
return '\u03b8=%0.3f\u03c0 (%0.3f\u00b0), r=%0.3f' % (theta, theta * 180.0, r)
s = '\u03b8=%0.3f\u03c0 (%0.3f\u00b0), r=%0.3f' % (theta, theta * 180.0, r)
s = s.encode( 'utf-8' )
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This shouldn't be necessary and probably indicates a bug somewhere else. Returning unicode from this function is actually what we want. Can you describe which backend/platform you were using when you can across this problem?

return s

def get_data_ratio(self):
'''
Expand Down
101 changes: 101 additions & 0 deletions lib/matplotlib/tests/test_axes.py
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Original file line number Diff line number Diff line change
Expand Up @@ -411,6 +411,107 @@ def test_polar_units():
assert_true(isinstance(plt.gca().get_xaxis().get_major_formatter(), units.UnitDblFormatter))


def test_polar_format_coord():
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This needs a @cleanup decorator so global state does not leak.

import matplotlib.testing.jpl_units as units
units.register()

deg = units.UnitDbl(1.0, "deg")
km = units.UnitDbl(1.0, "km")

fig = plt.figure()
ax = plt.subplot(111, polar=True)

# Make sure this doesn't throw any exceptions
ax.format_coord( 30.0*deg, 4.0*km )
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Can you PEP8 the whitespace here?



@image_comparison(baseline_images=['polar_rgrids'])
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As these tests add new image comparison tests, you'll also need to commit the new baseline images.

def test_polar_rgrids():
import matplotlib.testing.jpl_units as units
units.register()

pi = np.pi
deg = units.UnitDbl(1.0, "deg")
rad = units.UnitDbl(1.0, "rad")
km = units.UnitDbl(1.0, "km")

fig = plt.figure()

ax1 = plt.subplot(221, polar=True)
ax1.set_rgrids([45*deg, 90*deg], angle=60.0*deg)

ax2 = plt.subplot(222, polar=True)
ax2.set_rgrids([pi/4*rad, pi/2*rad], angle=60.0*deg)

ax3 = plt.subplot(223, polar=True)
ax3.set_rgrids([45*deg, 90*deg], angle=pi/3*rad)

ax4 = plt.subplot(224, polar=True)
ax4.set_rgrids([pi/4*rad, pi/2*rad], angle=pi/3*rad)


@image_comparison(baseline_images=['polar_rticks'])
def test_polar_rticks():
import matplotlib.testing.jpl_units as units
units.register()

pi = np.pi
deg = units.UnitDbl(1.0, "deg")
rad = units.UnitDbl(1.0, "rad")
km = units.UnitDbl(1.0, "km")

fig = plt.figure()

ax = plt.subplot(111, polar=True)
ax.set_rticks([1.5*km, 3.0*km, 4.5*km])

x1 = [30.0*deg, 45.0*deg, 60.0*deg, 90.0*deg]
y1 = [1.0*km, 2.0*km, 3.0*km, 4.0*km]

ax.plot( x1, y1 )


@image_comparison(baseline_images=['polar_teta_offset'])
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teta -> theta

def test_polar_theta_offset():
import matplotlib.testing.jpl_units as units
units.register()

pi = np.pi
deg = units.UnitDbl(1.0, "deg")
rad = units.UnitDbl(1.0, "rad")
km = units.UnitDbl(1.0, "km")

fig = plt.figure()

ax1 = plt.subplot(211, polar=True)
ax1.set_theta_offset(45*deg)

ax2 = plt.subplot(212, polar=True)
ax2.set_theta_offset(pi/4*rad)


@image_comparison(baseline_images=['polar_tetagrids'])
def test_polar_thetagrids():
import matplotlib.testing.jpl_units as units
units.register()

pi = np.pi
deg = units.UnitDbl(1.0, "deg")
rad = units.UnitDbl(1.0, "rad")
km = units.UnitDbl(1.0, "km")

fig = plt.figure()

ax1 = plt.subplot(311, polar=True)
ax1.set_thetagrids([90*deg, 180*deg])

ax2 = plt.subplot(312, polar=True)
ax2.set_thetagrids([pi/2*rad, pi*rad])

ax3 = plt.subplot(313, polar=True)
ax3.set_thetagrids([90.0, 180.0])


@image_comparison(baseline_images=['polar_rmin'])
def test_polar_rmin():
r = np.arange(0, 3.0, 0.01)
Expand Down