Feb 16, 2020 · Feb 10, 2020 · Feb 16, 2020 · Feb 16, 2020
diff --git a/doc/api/next_api_changes/behaviour.rst b/doc/api/next_api_changes/behaviour.rst
 extra letters or characters in the "middle" of the string, e.g. ``"(0, 1a, '0.5')"``
 would be interpreted as ``(0, 1, 0.5)``.  These extra characters (including the
 internal quotes) now cause a ValueError to be raised.

 `.SymLogNorm` now has a *base* parameter
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 Previously, `.SymLogNorm` had no *base* kwarg, and defaulted to ``base=np.e``
 whereas the documentation said it was ``base=10``.  In preparation to make
 the default 10, calling `.SymLogNorm` without the new *base* kwarg emits a
 deprecation warning.
diff --git a/examples/userdemo/colormap_normalizations.py b/examples/userdemo/colormap_normalizations.py

 pcm = ax[0].pcolormesh(X, Y, Z1,
                       norm=colors.SymLogNorm(linthresh=0.03, linscale=0.03,
                                              vmin=-1.0, vmax=1.0),
                                              vmin=-1.0, vmax=1.0, base=10),
                       cmap='RdBu_r')
 fig.colorbar(pcm, ax=ax[0], extend='both')

diff --git a/examples/userdemo/colormap_normalizations_symlognorm.py b/examples/userdemo/colormap_normalizations_symlognorm.py

 pcm = ax[0].pcolormesh(X, Y, Z,
                       norm=colors.SymLogNorm(linthresh=0.03, linscale=0.03,
                                              vmin=-1.0, vmax=1.0),
                                              vmin=-1.0, vmax=1.0, base=10),
                       cmap='RdBu_r')
 fig.colorbar(pcm, ax=ax[0], extend='both')

diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
    *linthresh* allows the user to specify the size of this range
    (-*linthresh*, *linthresh*).
    """
    def __init__(self, linthresh, linscale=1.0,
 vmin=None, vmax=None, clip=False):
    def __init__(self, linthresh, linscale=1.0, vmin=None, vmax=None,
 clip=False, *, base=None):
        """
        Parameters
        ----------
        linscale : float, default: 1
            This allows the linear range (-*linthresh* to *linthresh*) to be
            stretched relative to the logarithmic range. Its value is the
            number of decades to use for each half of the linear range. For
            example, when *linscale* == 1.0 (the default), the space used for
            the positive and negative halves of the linear range will be equal
            to one decade in the logarithmic range.
            number of powers of *base* (decades for base 10) to use for each
            half of the linear range. For example, when *linscale* == 1.0
            (the default), the space used for the positive and negative halves
            of the linear range will be equal to a decade in the logarithmic
            range if ``base=10``.
        base : float, default: None
            For v3.2 the default is the old value of ``np.e``, but that is
            deprecated for v3.3 when base will default to 10.  During the
            transition, specify the *base* kwarg to avoid a deprecation
            warning.
        """
        Normalize.__init__(self, vmin, vmax, clip)
        if base is None:
            self._base = np.e
            cbook.warn_deprecated("3.3", message="default base will change "
                "from np.e to 10.  To suppress this warning specify the base "
                "kwarg.")
        else:
            self._base = base
        self._log_base = np.log(self._base)

        self.linthresh = float(linthresh)
        self._linscale_adj = (linscale / (1.0 -np.e ** -1))
        self._linscale_adj = (linscale / (1.0 -self._base ** -1))
        if vmin is not None and vmax is not None:
            self._transform_vmin_vmax()

        with np.errstate(invalid="ignore"):
            masked = np.abs(a) > self.linthresh
        sign = np.sign(a[masked])
        log = (self._linscale_adj + np.log(np.abs(a[masked]) / self.linthresh))
        log = (self._linscale_adj +
               np.log(np.abs(a[masked]) / self.linthresh) / self._log_base)
        log *= sign * self.linthresh
        a[masked] = log
        a[~masked] *= self._linscale_adj
        """Inverse inplace Transformation."""
        masked = np.abs(a) > (self.linthresh * self._linscale_adj)
        sign = np.sign(a[masked])
        exp = np.exp(sign * a[masked] / self.linthresh - self._linscale_adj)
        exp = np.power(self._base,
                       sign * a[masked] / self.linthresh - self._linscale_adj)
        exp *= sign * self.linthresh
        a[masked] = exp
        a[~masked] /= self._linscale_adj
diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py
    """
    Test SymLogNorm behavior
    """
    norm = mcolors.SymLogNorm(3, vmax=5, linscale=1.2)
    norm = mcolors.SymLogNorm(3, vmax=5, linscale=1.2, base=np.e)
    vals = np.array([-30, -1, 2, 6], dtype=float)
    normed_vals = norm(vals)
    expected = [0., 0.53980074, 0.826991, 1.02758204]
    _mask_tester(norm, vals)

    # Ensure that specifying vmin returns the same result as above
    norm = mcolors.SymLogNorm(3, vmin=-30, vmax=5, linscale=1.2)
    norm = mcolors.SymLogNorm(3, vmin=-30, vmax=5, linscale=1.2, base=np.e)
    normed_vals = norm(vals)
    assert_array_almost_equal(normed_vals, expected)

    # test something more easily checked.
    norm = mcolors.SymLogNorm(1, vmin=-np.e**3, vmax=np.e**3, base=np.e)
    nn = norm([-np.e**3, -np.e**2, -np.e**1, -1,
              0, 1, np.e**1, np.e**2, np.e**3])
    xx = np.array([0., 0.109123, 0.218246, 0.32737, 0.5, 0.67263,
                   0.781754, 0.890877, 1.])
    assert_array_almost_equal(nn, xx)
    norm = mcolors.SymLogNorm(1, vmin=-10**3, vmax=10**3, base=10)
    nn = norm([-10**3, -10**2, -10**1, -1,
              0, 1, 10**1, 10**2, 10**3])
    xx = np.array([0., 0.121622, 0.243243, 0.364865, 0.5, 0.635135,
                   0.756757, 0.878378, 1.])
    assert_array_almost_equal(nn, xx)


 def test_SymLogNorm_colorbar():
    """
    Test un-called SymLogNorm in a colorbar.
    """
    norm = mcolors.SymLogNorm(0.1, vmin=-1, vmax=1, linscale=1)
    norm = mcolors.SymLogNorm(0.1, vmin=-1, vmax=1, linscale=1, base=np.e)
    fig = plt.figure()
    mcolorbar.ColorbarBase(fig.add_subplot(111), norm=norm)
    plt.close(fig)
    Test SymLogNorm to ensure it is not adding sub-ticks to zero label
    """
    fig = plt.figure()
    norm = mcolors.SymLogNorm(1e-5, vmin=-1, vmax=1)
    norm = mcolors.SymLogNorm(1e-5, vmin=-1, vmax=1, base=np.e)
    cbar = mcolorbar.ColorbarBase(fig.add_subplot(111), norm=norm)
    ticks = cbar.get_ticks()
    assert sum(ticks == 0) == 1
    mydata = data.view(MyArray)

    for norm in [mcolors.Normalize(), mcolors.LogNorm(),
                 mcolors.SymLogNorm(3, vmax=5, linscale=1),
                 mcolors.SymLogNorm(3, vmax=5, linscale=1, base=np.e),
                 mcolors.Normalize(vmin=mydata.min(), vmax=mydata.max()),
                 mcolors.SymLogNorm(3, vmin=mydata.min(), vmax=mydata.max()),
                 mcolors.SymLogNorm(3, vmin=mydata.min(), vmax=mydata.max(),
                                    base=np.e),
                 mcolors.PowerNorm(1)]:
        assert_array_equal(norm(mydata), norm(data))
        fig, ax = plt.subplots()
diff --git a/tutorials/colors/colormapnorms.py b/tutorials/colors/colormapnorms.py

 pcm = ax[0].pcolormesh(X, Y, Z,
                       norm=colors.SymLogNorm(linthresh=0.03, linscale=0.03,
                                              vmin=-1.0, vmax=1.0),
                                              vmin=-1.0, vmax=1.0, base=10),
                       cmap='RdBu_r')
 fig.colorbar(pcm, ax=ax[0], extend='both')
Original file line number	Diff line number	Diff line change
Expand Up		@@ -85,3 +85,11 @@ Previously, rcParams entries whose values were color-like accepted "spurious"
		extra letters or characters in the "middle" of the string, e.g. ``"(0, 1a, '0.5')"``
		would be interpreted as ``(0, 1, 0.5)``. These extra characters (including the
		internal quotes) now cause a ValueError to be raised.

		`.SymLogNorm` now has a base parameter
		~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

		Previously, `.SymLogNorm` had no base kwarg, and defaulted to ``base=np.e``
		whereas the documentation said it was ``base=10``. In preparation to make
		the default 10, calling `.SymLogNorm` without the new base kwarg emits a
		deprecation warning.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -69,7 +69,7 @@

		pcm = ax[0].pcolormesh(X, Y, Z1,
		norm=colors.SymLogNorm(linthresh=0.03, linscale=0.03,
		vmin=-1.0, vmax=1.0),
		vmin=-1.0, vmax=1.0, base=10),
		cmap='RdBu_r')
		fig.colorbar(pcm, ax=ax[0], extend='both')

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -29,7 +29,7 @@

		pcm = ax[0].pcolormesh(X, Y, Z,
		norm=colors.SymLogNorm(linthresh=0.03, linscale=0.03,
		vmin=-1.0, vmax=1.0),
		vmin=-1.0, vmax=1.0, base=10),
		cmap='RdBu_r')
		fig.colorbar(pcm, ax=ax[0], extend='both')

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1202,8 +1202,8 @@ class SymLogNorm(Normalize):
		linthresh allows the user to specify the size of this range
		(-linthresh, linthresh).
		"""
		def __init__(self, linthresh, linscale=1.0,
		vmin=None, vmax=None, clip=False):
		def __init__(self, linthresh, linscale=1.0, vmin=None, vmax=None,
		clip=False, *, base=None):
		"""
		Parameters
		----------
Expand All		@@ -1213,14 +1213,29 @@ def __init__(self, linthresh, linscale=1.0,
		linscale : float, default: 1
		This allows the linear range (-linthresh to linthresh) to be
		stretched relative to the logarithmic range. Its value is the
		number of decades to use for each half of the linear range. For
		example, when linscale == 1.0 (the default), the space used for
		the positive and negative halves of the linear range will be equal
		to one decade in the logarithmic range.
		number of powers of base (decades for base 10) to use for each
		half of the linear range. For example, when linscale == 1.0
		(the default), the space used for the positive and negative halves
		of the linear range will be equal to a decade in the logarithmic
		range if ``base=10``.
		base : float, default: None
		For v3.2 the default is the old value of ``np.e``, but that is
		deprecated for v3.3 when base will default to 10. During the
		transition, specify the base kwarg to avoid a deprecation
		warning.
		"""
		Normalize.__init__(self, vmin, vmax, clip)
		if base is None:
		self._base = np.e
		cbook.warn_deprecated("3.3", message="default base will change "
		"from np.e to 10. To suppress this warning specify the base "
		"kwarg.")
		else:
		self._base = base
		self._log_base = np.log(self._base)

		self.linthresh = float(linthresh)
		self._linscale_adj = (linscale / (1.0 -np.e ** -1))
		self._linscale_adj = (linscale / (1.0 -self._base ** -1))
		if vmin is not None and vmax is not None:
		self._transform_vmin_vmax()

Expand DownExpand Up		@@ -1255,7 +1270,8 @@ def _transform(self, a):
		with np.errstate(invalid="ignore"):
		masked = np.abs(a) > self.linthresh
		sign = np.sign(a[masked])
		log = (self._linscale_adj + np.log(np.abs(a[masked]) / self.linthresh))
		log = (self._linscale_adj +
		np.log(np.abs(a[masked]) / self.linthresh) / self._log_base)
		log = sign self.linthresh
		a[masked] = log
		a[~masked] *= self._linscale_adj
Expand All		@@ -1265,7 +1281,8 @@ def _inv_transform(self, a):
		"""Inverse inplace Transformation."""
		masked = np.abs(a) > (self.linthresh * self._linscale_adj)
		sign = np.sign(a[masked])
		exp = np.exp(sign * a[masked] / self.linthresh - self._linscale_adj)
		exp = np.power(self._base,
		sign * a[masked] / self.linthresh - self._linscale_adj)
		exp = sign self.linthresh
		a[masked] = exp
		a[~masked] /= self._linscale_adj
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -398,7 +398,7 @@ def test_SymLogNorm():
		"""
		Test SymLogNorm behavior
		"""
		norm = mcolors.SymLogNorm(3, vmax=5, linscale=1.2)
		norm = mcolors.SymLogNorm(3, vmax=5, linscale=1.2, base=np.e)
		vals = np.array([-30, -1, 2, 6], dtype=float)
		normed_vals = norm(vals)
		expected = [0., 0.53980074, 0.826991, 1.02758204]
Expand All		@@ -408,16 +408,30 @@ def test_SymLogNorm():
		_mask_tester(norm, vals)

		# Ensure that specifying vmin returns the same result as above
		norm = mcolors.SymLogNorm(3, vmin=-30, vmax=5, linscale=1.2)
		norm = mcolors.SymLogNorm(3, vmin=-30, vmax=5, linscale=1.2, base=np.e)
		normed_vals = norm(vals)
		assert_array_almost_equal(normed_vals, expected)

		# test something more easily checked.
		norm = mcolors.SymLogNorm(1, vmin=-np.e3, vmax=np.e3, base=np.e)
		nn = norm([-np.e3, -np.e2, -np.e**1, -1,
		0, 1, np.e1, np.e2, np.e**3])
		xx = np.array([0., 0.109123, 0.218246, 0.32737, 0.5, 0.67263,
		0.781754, 0.890877, 1.])
		assert_array_almost_equal(nn, xx)
		norm = mcolors.SymLogNorm(1, vmin=-103, vmax=103, base=10)
		nn = norm([-103, -102, -10**1, -1,
		0, 1, 101, 102, 10**3])
		xx = np.array([0., 0.121622, 0.243243, 0.364865, 0.5, 0.635135,
		0.756757, 0.878378, 1.])
		assert_array_almost_equal(nn, xx)


		def test_SymLogNorm_colorbar():
		"""
		Test un-called SymLogNorm in a colorbar.
		"""
		norm = mcolors.SymLogNorm(0.1, vmin=-1, vmax=1, linscale=1)
		norm = mcolors.SymLogNorm(0.1, vmin=-1, vmax=1, linscale=1, base=np.e)
		fig = plt.figure()
		mcolorbar.ColorbarBase(fig.add_subplot(111), norm=norm)
		plt.close(fig)
Expand All		@@ -428,7 +442,7 @@ def test_SymLogNorm_single_zero():
		Test SymLogNorm to ensure it is not adding sub-ticks to zero label
		"""
		fig = plt.figure()
		norm = mcolors.SymLogNorm(1e-5, vmin=-1, vmax=1)
		norm = mcolors.SymLogNorm(1e-5, vmin=-1, vmax=1, base=np.e)
		cbar = mcolorbar.ColorbarBase(fig.add_subplot(111), norm=norm)
		ticks = cbar.get_ticks()
		assert sum(ticks == 0) == 1
Expand DownExpand Up		@@ -905,9 +919,10 @@ def __add__(self, other):
		mydata = data.view(MyArray)

		for norm in [mcolors.Normalize(), mcolors.LogNorm(),
		mcolors.SymLogNorm(3, vmax=5, linscale=1),
		mcolors.SymLogNorm(3, vmax=5, linscale=1, base=np.e),
		mcolors.Normalize(vmin=mydata.min(), vmax=mydata.max()),
		mcolors.SymLogNorm(3, vmin=mydata.min(), vmax=mydata.max()),
		mcolors.SymLogNorm(3, vmin=mydata.min(), vmax=mydata.max(),
		base=np.e),
		mcolors.PowerNorm(1)]:
		assert_array_equal(norm(mydata), norm(data))
		fig, ax = plt.subplots()
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -98,7 +98,7 @@

		pcm = ax[0].pcolormesh(X, Y, Z,
		norm=colors.SymLogNorm(linthresh=0.03, linscale=0.03,
		vmin=-1.0, vmax=1.0),
		vmin=-1.0, vmax=1.0, base=10),
		cmap='RdBu_r')
		fig.colorbar(pcm, ax=ax[0], extend='both')

Expand Down